Georgina Page
email: georgina.page@porthosp.nhs.uk

Dr David Laight

Prof Mike H Cummings

Georgina ; Page

Alexandra Queen

Dr Glj Page

Dr Georgina Page

Thiamine deficiency in diabetes mellitus and the impact of thiamine replacement on glucose metabolism and vascular disease

come

Thiamine deficiency in diabetes mellitus and the impact of thiamine on glucose metabolism and vascular disease

Introduction

The pathogenesis of vascular complications in diabetes is a much debated subject and despite extensive research no unifying mechanism has been discovered. Several hypotheses exist: capillary hypertension, insulin resistance syndrome, endothelial dysfunction, increased vascular inflammation and oxidative stress with advanced glycation end product (AGE) formation. While these are all important processes it would appear that one is not exclusive of the other and it is more likely that all the above processes are integrally related. Figure 1 shows the relationship between these processes and how they act synergistically to promote the development of diabetes and vascular disease. Current therapies not only target traditional cardiovascular risk factors such as dyslipidaemia and hypertension but novel risk factors such as oxidative stress, endothelial dysfunction and inflammation. Thiamine is an example of a treatment that is known to affect these novel processes but with little evidence as to how it affects cardiovascular risk. This article aims to review the way in which thiamine deficiency occurs in diabetes and how replacement may lead to changes in vascular risk and vascular disease.

Thiamine

Thiamine is a member of the B-vitamin family and was the first water-soluble vitamin to be discovered in 1912 and isolated in 1926. Humans cannot synthesize thiamine and so a regular intake of thiamine, from exogenous sources, yeasts and plants, is necessary to maintain body stores and the recommended daily intake for adults is between 1 and 1.4 mg/day. Thiamine is absorbed from the diet in the proximal part of the small intestine into the enterocyte via either simple diffusion or trans-phosphorylation to thiamine monophosphate (TMP) but the majority occurs through active transport [START_REF] Rindi | Thiamine intestinal transport and related issues: recent aspects[END_REF]. This active transport involves a carrier-mediated process that is believed to involve the human thiamine transporters hTHTR-1 and hTHTR-2. It is subsequently phosphorylated to thiamine diphosphate, the most abundant compound in the body, an essential coenzyme for the transketolase enzyme and the dehydrogenase complexes for pyruvate, alpha-ketoglutarate and branched-chain keto acids. All of these enzymes are essential in carbohydrate metabolism.

Thiamine is excreted through the kidneys, where hTHTR-1 and hTHTR-2 are involved in the re-uptake of thiamine in the proximal tubules. These are adaptively up-regulated in thiamine deficiency via transcriptional regulatory mechanisms, and thus the kidneys are responsible for thiamine homeostasis [START_REF] Ashokkumar | Thiamin uptake by the human-derived renal epithelial (HEK-293) cells: cellular and molecular mechanisms[END_REF]. The thiamine transporters are also necessary for the uptake and regulation of thiamine in the pancreas where it essential for its normal endocrine function [START_REF] Mee | Pancreatic beta cells and islets take up thiamin by a regulated carrier-mediated process: studies using mice and human pancreatic preparations[END_REF].

Thiamine status can be assessed directly by measuring thiamine levels in blood or urinary excretion before and after loading [4]. Alternatively a functional measure of thiamine status, erythrocyte transketolase activity can be measured, but this is influenced by many other factors other than thiamine deficiency, is relatively unstable on sampling and there is a lack of agreement over the upper limit of the reference range [START_REF] Talwar | Vitamin B(1) status assessed by direct measurement of thiamin pyrophosphate in erythrocytes or whole blood by HPLC: comparison with erythrocyte transketolase activation assay[END_REF]. Microbiological assays measure red cell thiamine concentration but are time consuming and the sensitivity of the assays is not always sufficient for analyses of human body fluids [START_REF] Tallaksen | Determination of thiamin and its phosphate esters in human blood, plasma, and urine[END_REF]. The majority of the total thiamine content of whole blood is found in erythrocytes as TDP and has been shown to be a good indicator of body stores as it depletes at a rate similar to those of major organs. High performance liquid chromatography (HPLC) measurement of blood TDP levels has been determined to be a simple and precise way of assessing thiamine status [START_REF] Lu | Rapid HPLC measurement of thiamine and its phosphate esters in whole blood[END_REF].

Thiamine deficiency

Deficiency can occur as a result of inadequate intake, increased requirements (fever, pregnancy, breast feeding), excessive renal loss, consumption of anti-thiamine factors (tea, coffee, raw shellfish), or a combination of these factors. Severe deficiency results in beri-beri, which is termed, wet, dry, or cerebral (commonly known as Wernicke's Encephalopathy) depending on the system affected. In the western world Wernicke's Encephalopathy is most commonly associated with chronic alcoholism as a result of both a nutritional and absorptive deficiency.

Studies into Wernicke's Encephalopathy have shown the neuro-degeneration that occurs is strongly associated with increased endothelial nitric oxide synthase (eNOS) production, inter-cellular adhesion molecule 1 (ICAM-1) levels and the production of reactive oxygen species. It is not currently clear whether eNOS production induces neuronal damage through peroxynitrite formation or has a neuroprotective role in response to local inflammation [START_REF] Palma | Endothelial nitric oxide synthase overexpression by neuronal cells in neurodegeneration: a link between inflammation and neuroprotection[END_REF]. There has also been shown to be a breakdown in the blood-brain barrier as a result of endothelial dysfunction, and decreased cerebral energy due to impaired glucose metabolism, which occurs as a result of decreased activity of α-ketoglutarate dehydrogenase. Finally increased pro-inflammatory cytokines have been demonstrated in the thiamine deficient brain [START_REF] Hazell | Update of cell damage mechanisms in thiamine deficiency: focus on oxidative stress, excitotoxicity and inflammation[END_REF]. All of these pathological processes seen in the thiamine deficient brain are strongly associated with pathophysiology of insulin resistance and macrovascular disease [START_REF] Stehouwer | The pathogenesis of vascular complications of diabetes mellitus: one voice or many? European journal of clinical investigation[END_REF][START_REF] Hartge | Endothelial dysfunction and its role in diabetic vascular disease[END_REF].

A Cochrane review has demonstrated a lack of evidence as to the dose, frequency, route or duration of thiamine treatment for prophylaxis against or treatment of Wernicke's Encephalopathy in people at risk from alcohol abuse [START_REF] Day | Thiamine for Wernicke-Korsakoff Syndrome in people at risk from alcohol abuse[END_REF]. However the Royal College of Physicians published guidelines advising treatment of at risk patients with high-dose parenteral thiamine to prevent the mortality associated with Wernicke's Encephalopathy and the development of Korsakoff's Psychosis [START_REF] Thomson | The Royal College of Physicians report on alcohol: guidelines for managing Wernicke's encephalopathy in the accident and Emergency Department[END_REF].

Thiamine deficiency and diabetes mellitus -evidence, mechanisms and replacement

Evidence

Several studies have demonstrated thiamine deficiency in individuals with both type 1 and type 2 diabetes. Studies have shown altered erythrocyte transketolase activity indicating a risk of thiamine deficiency in both type 1 and type 2 diabetes, but the proportion of affected individuals varies from 17% to 79% across the studies [START_REF] Jermendy | Evaluating thiamine deficiency in patients with diabetes[END_REF][START_REF] Saito | Blood thiamine levels in outpatients with diabetes mellitus[END_REF][START_REF] Lemoine | Vitamin B1, B2, B6, and C status in hospital inpatients[END_REF]. In addition, when comparing people with diabetes with the normal population, there was found to be no significant difference between erythrocyte transketolase activity levels in one study [START_REF] Thornalley | High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease[END_REF] but levels indicating a significantly higher risk of thiamine deficiency in another study [START_REF] Jermendy | Evaluating thiamine deficiency in patients with diabetes[END_REF] . Measurement of thiamine levels and its esters in blood, serum and plasma also reveals differing results across the studies. Three studies have shown reduced plasma thiamine concentrations in patients with diabetes [START_REF] Saito | Blood thiamine levels in outpatients with diabetes mellitus[END_REF][START_REF] Thornalley | High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease[END_REF][START_REF] Valerio | Lipophilic thiamine treatment in long-standing insulin-dependent diabetes mellitus[END_REF], however red cell thiamine levels were low in 15% of patients with diabetes in one study [START_REF] Vindedzis | Thiamine deficiency in diabetes -is diet relevant?[END_REF] but normal in another [START_REF] Thornalley | High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease[END_REF].

The reasons for these differing results are not well understood. While some may be down to sampling and assay problems as described previously, not all the studies comment on the alcohol intake in the individuals or other potential causes of thiamine deficiency. Only the Jermendy and Thornalley papers [START_REF] Jermendy | Evaluating thiamine deficiency in patients with diabetes[END_REF][START_REF] Thornalley | High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease[END_REF] specifically sited excess alcohol intake as an exclusion criteria, but direct comparison of these two papers reveal opposing results in erythrocyte transketolase activity as described above. In summary, whilst there is evidence of thiamine deficiency in individuals with diabetes, the prevalence is not known and further studies should be undertaken to determine this.

Mechanisms

The reason for this deficiency is not well understood but several mechanisms may be responsible. Insulin deficiency is associated with a reduction in the rate of thiamine transport across the intestine and insulin deficient rats have been shown to have a net reduction in the transport of free thiamine and TMP but with a corresponding increase in TDP levels [START_REF] Patrini | Effect of insulin on thiamine intestinal transport in rat everted jejunal sacs[END_REF]. Conversely thiamine deficiency leads to a marked impairment in insulin synthesis and secretion [START_REF] Mee | Pancreatic beta cells and islets take up thiamin by a regulated carrier-mediated process: studies using mice and human pancreatic preparations[END_REF] thereby insulin deficiency may exacerbate thiamine deficiency and vice-versa.

Thornalley showed that in the thiamine deficient state there is increased renal clearance and fractional excretion of thiamine and it has been hypothesised that this is secondary to decreased re-uptake of thiamine in renal proximal tubules, possibly an early marker of renal proximal tubule dysfunction in diabetes [START_REF] Thornalley | High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease[END_REF]. However a further study has shown increased plasma thiamine levels with progressive renal impairment and proteinuria suggesting decreased renal clearance of thiamine [START_REF] Pacal | Role of thiamine status and genetic variability in transketolase and other pentose phosphate cycle enzymes in the progression of diabetic nephropathy[END_REF]. The reason for these differing results remains unclear and may be due to changes in the number and/or function of thiamine transporter proteins or due to increased or reduced filtration. Altered functioning of thiamine transporter proteins could, in theory, affect the hTHTR-1 and 2 proteins in both the gut and pancreas, with a reduction in active thiamine absorption and reduced pancreatic endocrine function, thus exacerbating both thiamine deficiency and hyperglycaemia.

Replacement

Thiamine supplementation (>4mg per day) has been shown to normalise red cell thiamine levels in patients with diabetes, whereas increasing dietary thiamine intake above the recommended dietary intake of 1 to 1.4mg/day have not -suggesting a need for higher than normal thiamine intake in patients with diabetes compared with normal individuals [START_REF] Vindedzis | Thiamine deficiency in diabetes -is diet relevant?[END_REF]. Oral thiamine replacement is widely available in the UK as thiamine hydrochloride, a water soluble compound. Benfotiamine is a lipid-soluble allithiamine derivative that has better intestinal absorption and improved bioavailability but it is not currently available for prescription in the UK [START_REF] Schreeb | Comparative bioavailability of two vitamin B1 preparations: benfotiamine and thiamine mononitrate[END_REF]. In one study five patients, who were treated with benfotiamine for seven days, showed a significant improvement in erythrocyte transketolase activity. This suggests an improvement in thiamine status [START_REF] Jermendy | Evaluating thiamine deficiency in patients with diabetes[END_REF], however this is a very small study and further work is necessary in this area,

Thiamine and hyperglycaemia -mechanisms of damage

Thiamine diphosphate is essential for carbohydrate metabolism. In the thiamine deficient state glucose undergoes metabolism via alternate pathways which can result in vascular damage. These pathways are summarised in figure 2. ) and reduced flux through the pentose phosphate pathway with subsequent increased flux through the alternative pathways of glucose metabolism [START_REF] Brownlee | Biochemistry and molecular cell biology of diabetic complications[END_REF].

Adapted from Brownlee 2001 [START_REF] Brownlee | Biochemistry and molecular cell biology of diabetic complications[END_REF] and Hammes 2003 [24] Several studies have been undertaken looking at the effect of thiamine and benfotiamine administration on these biochemical pathways. Animal studies have shown that high dose thiamine reduces activity through the hexosamine pathway [START_REF] Babaei-Jadidi | Highdose thiamine therapy counters dyslipidaemia in streptozotocin-induced diabetic rats[END_REF]. Thiamine supplementation can prevent hyperglycaemia driven reductions in cell replication and proliferation as well as decreasing AGE formation and reducing lactate levels [START_REF] Selva | Thiamine corrects delayed replication and decreases production of lactate and advanced glycation end-products in bovine retinal and human umbilical vein endothelial cells cultured under high glucose conditions[END_REF]. In vitro studies with benfotiamine and thiamine have shown a reduction in protein kinase C activation in the glomeruli and decreased glomerular AGE levels [START_REF] Babaei-Jadidi | Prevention of incipient diabetic nephropathy by high-dose thiamine and benfotiamine[END_REF]. Benfotiamine has been shown to prevent increased markers of hexosamine pathway activity, intracellular AGE formation, intracellular protein kinase C activity and NF-κB activation seen with in vitro hyperglycaemic damage [START_REF] Hammes | Benfotiamine blocks three major pathways of hyperglycemic damage and prevents experimental diabetic retinopathy[END_REF]. Oral benfotiamine in combination` with the anti-oxidant α-lipoic acid treatment normalises production of angiopoietin-2, a marker of increased intracellular methylglyoxals in endothelial cells which contribute to AGE formation, and Nacetylglucose modified protein, a marker of hexosamine pathway activity [START_REF] Du | Oral benfotiamine plus alpha-lipoic acid normalises complication-causing pathways in type 1 diabetes[END_REF]. Both thiamine and benfotiamine have been shown to reduce AGE formation in experimental diabetes [START_REF] Karachalias | Increased protein damage in renal glomeruli, retina, nerve, plasma and urine and its prevention by thiamine and benfotiamine therapy in a rat model of diabetes[END_REF]. Treatment with both thiamine and benfotiamine has been shown to reduce activation of the polyol pathway of glucose metabolism and to increase transketolase expression in the presence of hyperglycaemia [START_REF] Berrone | Regulation of intracellular glucose and polyol pathway by thiamine and benfotiamine in vascular cells cultured in high glucose[END_REF].

Collectively this data suggests that administration of thiamine or a derivative can influence carbohydrate metabolism by reducing metabolism through the alternate pathways of metabolism and improving metabolism via the pentose-phosphate pathway. This has been demonstrated in diabetic animal models where treatment with thiamine reduced fasting glucose and HbA1c levels [START_REF] Thornalley | Prevention of decline in glycaemic control in streptozocin-induced diabetic rats by thiamine but not by Benfotiamine[END_REF] and also in humans with type 2 diabetes, where a short duration of treatment with thiamine (150mg per day for 1 month) showed a significant improvement in fasting glucose levels [START_REF] Gonzalez-Ortiz | Effect of thiamine administration on metabolic profile, cytokines and inflammatory markers in drug-naive patients with type 2 diabetes[END_REF].

Thiamine, endothelial function and oxidative stress

Multiple studies have looked at the effect of thiamine upon endothelial function and oxidative stress and several are summarised in table 1.

Study

Mode Salient points

Lukienko '00 [33] In vitro (rat liver cells)

Thiamine inhibits lipid peroxidation and oxidation of oleic acid Ascher '01 [34] In vitro

(bovine)
Thiamine inhibited hyperglycaemia driven endothelial cell activation and prevented the effects of hyperglycaemia on endothelial cell migration Arora '06 [35] In vivo

(humans)
Iv thiamine improved endothelium dependant vasodilatation in presence of hyperglycaemia Stirban et al '06 [36] In vivo

(humans)
BT prevented macro and micro vascular endothelial dysfunction Thornalley '07 [17] In vivo

(humans)
Negative correlation between plasma thiamine levels and VCAM-1

Wong '07 [37] In vivo

(humans)
Increased dietary thiamine intake associated with increased no of endothelial progenitor cells and improved vascular endothelial function Balakumar '08 [38] In vivo

(rats)
Benfotiamine prevented vascular endothelial dysfunction and oxidation stress.

Schmid et al '08 [39] In vitro (human, rat and porcine kidney cells)

Benfotiamine prevents oxidative stress Schupp '08 [40] In vivo

(humans)
Benfotiamine increased antioxidant capacity of plasma in dialysis patients.

Balakumar '09 [41] In vivo (rats)

Benfotiamine reduces the oxidative stress and enhances the generation of nitric oxide to prevent VED.

Verma '09 [42] In vivo (rats)

Benfotiamine prevented induced oxidative stress Table 1: Studies examining the effect of thiamine and benfotiamine on endothelial function and oxidative stress.

VCAM-1 = vascular cellular adhesion molecule; VED = vascular endothelial dysfunction

The antioxidant properties of thiamine have been known since the 1950's. This has been shown in foodstuffs where rye bread, containing a higher content of thiamine than wheat dough, has a higher antioxidant activity [START_REF] Martinez-Villaluenga | Effect of flour extraction rate and baking on thiamine and riboflavin content and antioxidant capacity of traditional rye bread[END_REF]. In 2000, Lukienko et al demonstrated that thiamine inhibited lipid peroxidation in vitro and Schmid et al demonstrated the antioxidant properties of benfotiamine in kidney cell lines [START_REF] Schmid | Benfotiamine exhibits direct antioxidative capacity and prevents induction of DNA damage in vitro[END_REF]. In vivo animal studies have shown benfotiamine can reduce oxidative stress when induced either through chemical means (sodium arsenite, nicotine or uric-acid) or diabetes [START_REF] Balakumar | Benfotiamine attenuates nicotine and uric acid-induced vascular endothelial dysfunction in the rat[END_REF][START_REF] Balakumar | Ameliorative effect of combination of benfotiamine and fenofibrate in diabetes-induced vascular endothelial dysfunction and nephropathy in the rat[END_REF][START_REF] Verma | The defensive effect of benfotiamine in sodium arsenite-induced experimental vascular endothelial dysfunction[END_REF]. The anti-oxidative capacity of benfotiamine has also been demonstrated in patients with diabetes and those undergoing dialysis [START_REF] Stirban | Benfotiamine prevents macro-and microvascular endothelial dysfunction and oxidative stress following a meal rich in advanced glycation end products in individuals with type 2 diabetes[END_REF][START_REF] Schupp | Benfotiamine reduces genomic damage in peripheral lymphocytes of hemodialysis patients[END_REF]. Improved endothelial function in a thiamine-rich environment has been demonstrated by a reversal of hyperglycaemia induced reduction in endothelial cell migration and proliferation. In addition increased von Willibrand factor levels, a marker of endothelial cell damage, are reduced when wounded endothelial cells are treated with thiamine [START_REF] Ascher | Thiamine reverses hyperglycemia-induced dysfunction in cultured endothelial cells[END_REF]. Animal models have shown benfotiamine reduces oxidative stress and activates endothelial nitric oxide synthase to enhance the generation and bioavailability of NO, subsequently improving the integrity of vascular endothelium and preventing induced experimental vascular endothelial dysfunction (VED) [START_REF] Balakumar | Ameliorative effect of combination of benfotiamine and fenofibrate in diabetes-induced vascular endothelial dysfunction and nephropathy in the rat[END_REF][START_REF] Verma | The defensive effect of benfotiamine in sodium arsenite-induced experimental vascular endothelial dysfunction[END_REF]. In individuals with diabetes there is a negative correlation between plasma thiamine levels and endothelial dysfunction [START_REF] Thornalley | High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease[END_REF][START_REF] Wong | Daily intake of thiamine correlates with the circulating level of endothelial progenitor cells and the endothelial function in patients with type II diabetes[END_REF] and endothelial dysfunction is prevented by both benfotiamine and thiamine [START_REF] Arora | Thiamine (vitamin B1) improves endothelium-dependent vasodilatation in the presence of hyperglycemia[END_REF][START_REF] Stirban | Benfotiamine prevents macro-and microvascular endothelial dysfunction and oxidative stress following a meal rich in advanced glycation end products in individuals with type 2 diabetes[END_REF].

This strong body of evidence demonstrates thiamine or its derivatives act as antioxidants and have a beneficial effect on endothelial function. These changes are seen in both the euglycaemic and hyperglycaemic environment.

Thiamine and vascular disease

Microalbuminuria, an early indicator of diabetic nephropathy, is associated with an increased cardiovascular risk in individuals with and without diabetes [START_REF] Stehouwer | Microalbuminuria and risk for cardiovascular disease: Analysis of potential mechanisms[END_REF]. In vitro studies with benfotiamine and thiamine have shown the ability to prevent microalbuminuria and proteinuria in diabetic rats. In vivo studies have shown that high dose oral supplementation with thiamine compared with placebo significantly reduces urinary albumin excretion in individuals [START_REF] Rabbani | Highdose thiamine therapy for patients with type 2 diabetes and microalbuminuria: a randomised, double-blind placebo-controlled pilot study[END_REF][START_REF] Riaz | Effect of high dose thiamine on the levels of urinary protein biomarkers in diabetes mellitus type 2[END_REF]. However reduction in microalbuminuria, with benfotiamine, was not evident in patients already receiving angiotensin converting enzyme inhibitors or angiotensin II receptor blockers [START_REF] Alkhalaf | trial on benfotiamine treatment in patients with diabetic nephropathy[END_REF].

Thiamine has been shown to prevent apoptosis of human retinal pericytes, loss of which represents an early stage in the development of diabetic retinopathy [START_REF] Beltramo | Thiamine and benfotiamine prevent apoptosis induced by high glucose-conditioned extracellular matrix in human retinal pericytes[END_REF]. In vivo studies have also shown benfotiamine treatment prevented the development of experimental diabetic retinopathy in rats [START_REF] Hammes | Benfotiamine blocks three major pathways of hyperglycemic damage and prevents experimental diabetic retinopathy[END_REF].

Thiamine has been demonstrated to have significant analgesic effects in neuropathic pain. In addition it has shown beneficial acute and chronic anti-inflammatory actions upon induced skin lesions [START_REF] Moallem | A study of acute and chronic antinociceptive and anti-inflammatory effects of thiamine in mice[END_REF]. Further studies in diabetic neuropathy have shown a beneficial effect of benfotiamine upon several modalities of neuropathic pain [START_REF] Sanchez-Ramirez | Benfotiamine relieves inflammatory and neuropathic pain in rats[END_REF] and another study in humans suggested benfotiamine improved pain in diabetic polyneuropathy [START_REF] Stracke | Benfotiamine in diabetic polyneuropathy (BENDIP): results of a randomised, double blind, placebocontrolled clinical study[END_REF].

Animal studies have shown that high dose thiamine, but not benfotiamine, therapy prevented diabetes-associated dyslipidaemia [START_REF] Babaei-Jadidi | Highdose thiamine therapy counters dyslipidaemia in streptozotocin-induced diabetic rats[END_REF].

Conclusions

It is well known that glucose metabolism is dependent upon thiamine as a cofactor and in the hyperglycaemic environment alternative pathways of metabolism (that are not thiamine dependant) are activated. This leads to increased formation of harmful by-products which contribute to the pathophysiology of diabetic complications. In addition thiamine has direct action on the endocrine function of the pancreas and, therefore, deficiency may contribute to hyperglycaemia through other mechanisms rather than impaired glucose metabolism.

Thiamine and its derivatives have been shown to improve endothelial function and reduce oxidative stress in both the normo-and hyperglycaemic environment. Given that these processes are closely linked with vascular inflammation it could be hypothesised that thiamine has anti-inflammatory properties. There is some evidence that this is seen in induced skin inflammation but vascular inflammation has not been extensively studied.

It has been demonstrated that thiamine has a beneficial effect upon several features of the metabolic syndrome such as microalbuminuria, a surrogate marker of vascular risk, and glycaemic control, and it could be hypothesised that thiamine supplementation may have beneficial effects upon integrally linked pathophysiological processes such as insulin resistance and hypertension.

All of the above processes are involved in the development of vascular complications in diabetes but it is not clear is whether thiamine therapy may have beneficial clinical effects in individuals with diabetes, through reducing cardiovascular risk and microvascular complications. It also remains to be determined whether any benefit that occurs is as a result of replacing thiamine in individuals who are prone to deficiency or by saturation and promotion of thiamine dependent pathways leading to an improvement in endothelial function and/or oxidative stress. All of these areas warrant further investigation.

Figure 2 :

 2 Figure 2: Diagram detailing pathways of glucose metabolism. Thiamine diphosphate is an essential cofactor for the enzymes depicted in italics. Inhibition of these enzymes results in increased superoxide production (O 2 -) and reduced flux through the pentose phosphate pathway with subsequent increased flux through the alternative pathways of glucose metabolism[START_REF] Brownlee | Biochemistry and molecular cell biology of diabetic complications[END_REF].

Figure 1 :

 1 Figure 1: Diagram showing the relationship between the metabolic syndrome and its components to oxidative stress, inflammation and endothelial dysfunction. All these processes contribute to atherosclerosis. Page 16 of 17

International Journal of Clinical PracticeInternational Journal of Clinical Practice

Acknowledgements

None


Rick A Veasey

Jonathan Hyde

Michael Lewis

Uday Trivedi

Andrew Cohen

Guy Lloyd

Stephen Furniss

Nikhil Patel

Neil Sulke
email: neil.sulke@esht.nhs.uk

Veasey Ra

Jaj + Hyde

ME + , Trivedi UH + , Cohen Ac + Lewis

Lloyd Gw

Furniss Ss

Patel Nr

Dr A N Sulke

It's good to talk! Changes in Coronary Revascularisation Practice In PCI Centres without Onsite Surgical Cover and the Impact of the Lifestream™ Angiography Video Conferencing System

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Percutaneous coronary intervention (PCI) activity has increased more than 6 fold in the last 15 years. Increased demand has been met by PCI centres without on-site surgical facilities. To improve communication between cardiologists and surgeons at a remote centre, we have developed a video conferencing system using standard internet links. The effect of this video data link (VDL) on referral pattern and patient selection for revascularisation was assessed prospectively after introduction of a joint cardiology conference (JCC) using the system.

Methods

Between 1 st October 2005 and 31 st March 2007, 1346 patients underwent diagnostic coronary angiography (CA). Of these, 114 patients were discussed at a cardiology conference (CC) attended by 3 consultant cardiologists (pre-VDL). In April 2007 the VDL system was introduced. Between 1 st April 2007 and 30 th September 2008, 1428 patients underwent diagnostic CA. Of these, 120 patients were discussed at a JCC attended by 4 consultant cardiologists and 2 consultant cardiothoracic surgeons (post-VDL). Following case-matching for patient demographics and coronary artery disease (CAD) severity and distribution, we assessed the effect upon management decisions arising from both the pre-and post-VDL JCC meetings.

Results

When comparing decision-making outcomes of post-VDL JCC with pre-VDL CC, significantly fewer patients were recommended for PCI (36.8% v 17.2% respectively, p=0.001) and significantly more patients were recommended for surgery (21.1% v 48.4% respectively, p<0.001). There were no significant differences in waiting times for PCI following JCC discussion, however, waiting times for surgical revascularisation were significantly reduced (140.9 ± 71.8 days vs 99.4 ± 56.6 days respectively, p=0.045).

Conclusions

The VDL system provides a highly practical method for PCI centres without onsite surgical cover to discuss complex patients requiring coronary revascularisation and significantly increases the number of patients referred for surgical revascularisation rather than PCI.

KEYWORDS

Percutaneous coronary intervention

Coronary artery bypass grafting

JCC

MDT

Video conferencing

What's known?

Percutaneous coronary intervention is increasingly performed in centres without onsite cardiac surgery facilities. Frequently, cases require multidisciplinary input from cardiologists and cardiac surgeons at remote sites.

What's new?

Video-data link technology enables real-time case discussion between cardiologists and cardiac surgeons at remote sites and introduction of this technology significantly influences revascularisation strategy and reduces waiting list times. met by PCI centres without on-site cardiac surgical facilities. Because of this significant increase in PCI activity, the British Cardiovascular Intervention Society (BCIS) recognises the need for additional PCI centres and that the majority of these will necessarily be provided by hospitals without on-site surgical cover. [START_REF] Dawkins | Percutaneous coronary intervention: recommendations for good practice and training[END_REF] Complicated and severe coronary artery disease has increasingly been treated with PCI as opposed to coronary artery bypass grafting (CABG), particularly since the advent of drug eluting stents. This is despite multiple trials demonstrating increased requirement for repeat revascularisation with PCI (3-7), as well as the fact that CABG has also shown long-term mortality benefits for certain categories of elective patients compared to PCI.(8-11) Well-defined groups of selected cases therefore warrant mandatory discussion between interventional cardiologists and cardiac surgeons before undertaking revascularisation procedures.(12) This has now been stated as a clear recommendation in a set of guidelines from the Society for Cardiothoracic Surgery in Great Britain & Ireland (SCTSGBI). With interventionalists and surgeons at remote centres such case discussion is both difficult and extremely time consuming to co-ordinate. Broadly speaking, the surgical 'hub' often provides cover to a variable number of PCI 'spokes'. To improve communication between interventional cardiologists and surgical colleagues at a remote centre, and therefore, hopefully optimise case selection for both PCI and CABG, we have developed a high definition angiogram video conferencing system using standard hospital broadband internet links. The effect of this system on referral pattern, patient selection and speed of appropriate revascularisation was assessed prospectively after introduction of a fortnightly video joint cardiac conference (JCC) using this technology, and was compared to previous practice.

Video-data link (VDL) Technology

The Lifestream TM Video Conferencing System allows transfer of coronary cineangiogram loops, in real time and at high definition image quality, over a secure standard hospital broadband (100mb) internet link. Bidirectional video/audio cameras enable live face-to-face case discussion between clinicians and their teams at both centres as 'picture-in-picture' technology, with no delay in image or sound transfer. The Lifestream™ system and user interface are shown in figure 1a and1b. For all patients included in the study, baseline demographics, cardiac risk factor profile and past medical history were recorded by case note review. Cardiac catheterisation procedures were reviewed and the number of diseased vessels documented as were the presence of disease of the proximal left anterior descending artery and left main stem.

Study population

Significant disease was defined as a luminal narrowing of greater than 50%.(9;13) Outcome decisions with regards patient management and revascularisation strategy from the JCC meetings for both patient cohorts (Pre-VDL and Post-VDL) were recorded. For the Pre-VDL patient cohort data were gathered retrospectively whereas data were gathered prospectively for the post-VDL patient cohort. Data were gathered from all patients undergoing diagnostic cardiac catheterisation and not just cases discussed at the JCC meetings, to investigate any changes in referral patterns for CA over the study time period. Time from the JCC meetings to percutaneous or surgical revascularisation was recorded, as well as mortality data.

Statistical analysis and study endpoints

The primary purpose of the data analyses was to determine whether there was a significant difference in revascularisation strategies between cases discussed before the

RESULTS

In total, 2774 patients were included in the study, with mean age 67.1 ± 10.9. Sex distribution included 60.8% males. Past medical history included hypertension (37.0%), diabetes mellitus (11.4%), cerebrovascular disease (3.8%), current or past smoking history (48.8%), myocardial infarction (18.0%), previous PCI (10.0%) and previous CABG (5.9%). There were no significant differences in these baseline demographics for the patient cohorts before and after introduction of the VDL (figure 2a).

Coronary angiography in the pre-and post-VDL patient cohorts demonstrated the following disease patterns: left main stem disease 5.0% v 6.7%, p=0.193; proximal left anterior descending artery disease 39.8% v 42.4%, p=0.357; three vessel disease 14.9% v 12.8%, p=0.275; two vessel disease 17.4% v 19.7%, p=0.279; impaired left ventricular function 29.9% v 35.5%, p=0.064 (figure 2b).

Cases referred to joint cardiac conference (JCC)

Two hundred and thirty-four cases were referred to JCC meetings. Of these, 114 of 1346 cases were from the pre-VDL group, and 120 of 1428 cases were from the post-VDL group. Patient demographics of these two cohorts are demonstrated in figure 3a, with no significant differences between the two groups.

Coronary angiography in the pre-VDL and post-VDL patient cohorts demonstrated the following disease patterns: left main stem disease 12.8% v 23.7%, p=0.096; proximal left anterior descending artery disease 69.6% v 67.8%, p=0.819; three vessel disease 25.3% v 4).

Multivariate analysis demonstrated that baseline demographics and coronary artery disease patterns were not independent predictors of percutaneous or surgical revascularisation, whereas discussion of cases at the VJCC as opposed to the CC was the only independent predictor of surgical revascularisation as a recommended management decision.

There were no significant differences in waiting times for PCI following JCC discussion between the pre-VDL and post-VDL patient cohorts (73.0 ± 44.6 days vs 76.4 ± 70.8 days respectively, p=0.849). However, there were significant differences in waiting times for surgical revascularisation following JCC discussion between the pre-VDL and post-VDL (140.9 ± 71.8 days vs 99.4 ± 56.6 days respectively, p=0.045).

DISCUSSION

Our study demonstrates the feasibility of conducting multidisciplinary team meetings between interventional cardiologists and cardiac surgeons at remote sites (the 'hub and spoke' concept). Over the time course of this study there were no significant differences in baseline characteristics of patients undergoing diagnostic coronary angiography. As would be expected, more severe disease patterns were discussed at the JCC meetings compared to the general study population of patients undergoing diagnostic coronary angiography. There were, however, no significant differences between the pre-VDL and post-VDL cohorts. The introduction of the video data link system, however, significantly changed revascularisation strategies and was an independent predictor of the requirement for surgical revascularisation. Use of the video data link, therefore, not only enables patients to have the most appropriate revascularisation strategy planned but our study also demonstrated that immediate multi-disciplinary case discussion significantly reduced waiting times to surgical intervention.

The guidelines of the SCTSGBI regarding the roles of multidisciplinary teams (MDT)

when discussing all cases for coronary revascularisation should not be underestimated, particularly with guidelines from BCIS to the same end. ( 2

Relevance to clinical practice

The boundaries between surgical and interventional disease patterns are progressively (and possibly controversially) changing. Historically, surgical revascularisation has been the recommended treatment option for severe coronary artery disease patterns, including multi-vessel and left main-stem disease).

The recently published Syntax trial is indicative of the increasingly complex coronary disease that is deemed suitable for either percutaneous or surgical revascularisation management strategies. [START_REF] Serruys | Percutaneous Coronary Intervention versus Coronary-Artery Bypass Grafting for Severe Coronary Artery Disease[END_REF] This trial randomised patients with left main stem disease and/or three vessel disease to PCI or CABG. This trial showed higher levels of repeat revascularisation for PCI but similar other major adverse clinical event (MACE) rates. A pre-requisite for this study was that coronary angiogram results were reviewed by both an interventional cardiologist and cardiac surgeon together to assess whether revascularisation could be adequately achieved by either PCI or CABG. However, approximately 25% of patients screened for this study had disease patterns or comorbidities that the cardiac surgeon and interventional cardiologist agreed should only be managed by a particular revascularisation strategy.

Not concluded by the authors, but perhaps of highest importance, is the definite need for multi-disciplinary discussion on a case-by-case basis. It is clear for logistical and practical reasons that this would be greatly facilitated by the use of video data links such as Lifestream TM . Multi-disciplinary case discussion could theoretically be achieved by other means but would undoubtedly require either interventional cardiologists or cardiac surgeons travelling to remote sites with considerable waste of senior clinicians' time and significant expense to the NHS. 16) However, data from the annual BCIS reports demonstrate that the need for emergency surgery fell from 2% in 1992 to 0.08% in 2007 (1;17), reflecting increasing technical expertise and safety regulation. With the consistent reductions in the need for emergency surgery, surgical cover is now provided by means of 'first available operating room', and cover is frequently provided by surgeons on standby at remote centres (15% of cases in 2004). The video data link utilised in this study also enables not only scheduled case conferences but also real time case discussion for emergency and complicated cases during the procedure itself.

Additional implications

The use of telecommunications to provide and facilitate medical care has been long acknowledged. [START_REF] Perednia | Telemedicine technology and clinical applications[END_REF] The utilisation of telemedicine to improve patient care within the NHS is recognised and encouraged in Lord Darzi's NHS Next Stage Review Report. [START_REF] Darzi | High Quality Care For All[END_REF] The Lifestream TM system and its utilisation as described in this study is one example of the vast number of ways in which patient care can be improved. The system can also be employed for a variety of other uses. In an era of significant time constraints on junior doctors' hours, education can be provided by live case demonstration of any case undertaken in the lab from cardiac catheterisation and complex intervention to

Study Limitations

This study involves comparison between two different patient populations, and whilst demographics between the groups are similar, there is the unavoidable potential of not controlling entirely for differences in patient demography and coronary artery disease patterns. There were no set criteria for referral to JCC meetings and it is possible that introduction of the video-data link changed patterns of patient referral to the JCC not accounted for in the described demographics.

CONCLUSIONS

The VDL system provides a highly practical method for PCI centres without onsite surgical cover to discuss complex patients requiring coronary revascularisation and significantly changes interventional practice patterns without hard-pressed surgeons or interventionalists being required to travel from their main work base. With the emergence of increasing numbers of PCI centres without onsite surgical cover, the routine use of the VDL system will ensure patients have adequate, early, and appropriate multidisciplinary discussion guiding revascularisation management. It is now recommended that it should be mandatory for all cases fulfilling certain basic criteria for revascularisation to be discussed at a MDT/JCC. Video systems such as the one discussed here (Lifestream TM ) surely must represent the only real and efficient option for delivery of these requirements.

INTRODUCTION

  Percutaneous coronary intervention (PCI) activity has increased more than 8 fold in the last 15 years throughout the United Kingdom.[START_REF] Ludman | BCIS audit returns. Adult intervention procedures[END_REF] This increased demand has been largely

METHODS

  The study was undertaken at Eastbourne District General Hospital, an interventional cardiology centre without on-site cardiac surgery. The nearest cardiac surgical centre is Royal Sussex County Hospital in Brighton, 19 miles or 40 minutes by road. The database for this study was populated by unselected patients undergoing diagnostic coronary angiography and cardiac catheterisation. The study was supported by an unrestricted research grant from Lifestream Medical Systems Ltd. The study sponsor had no involvement in collection or analysis of the data, results interpretation or preparation of the manuscript.

Between 1 st

 1 October 2005 and 31 st March 2007, 1346 patients underwent coronary angiography (CA). Of these 114 patients were referred for case discussion at a cardiology case conference (CC) attended by 3 consultant cardiologists (Pre-VDL cohort). In April September 2008, 1428 patients underwent CA. Of these 120 patients were discussed at a JCC (Post-VDL cohort) attended by 4 consultant cardiologists and at least 2 consultant cardiothoracic surgeons at a remote site (Royal Sussex County Hospital, Brighton).

  of the video data link and those discussed subsequently, controlling for patient demographics and coronary disease patterns. This was performed by first identifying factors that were associated with percutaneous or surgical revascularisation in univariate analyses and then using a multivariate model that controlled for significant risk factors while testing for significant differences in revascularisation strategy. Factors assessed as independent predictors included use of the video data link, baseline demographics and coronary artery disease patterns.Descriptive data were described using standard methods. Continuous variables are expressed as mean ± standard deviation. Comparison of groups was done using the independent samples t-test and the Mann-Whitney U-test depending on data distribution. Categorical variables were compared using the Chi squared test or Fisher's exact test. A p value < 0.05 was considered statistically significant.

  ;12) As such, case discussion by MDTs is advocated to improve quality and consensus and additionally is recommended by guidelines from the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS).(14)

  Of particular note for UK practice, BCIS guidelines recommend that 'PCI centres remote from surgical or tertiary centres should have facilities for real time image transfer to facilitate discussion and advice in individual cases'.(2) Formal cardiac surgical standby was a prerequisite for PCI when the technique of coronary angioplasty was first introduced.(

  ablation cases. Any electronically based information or imagery, including echocardiography, computed tomography imaging or magnetic resonance imaging can be communicated to remote sites by this method.

Figure 1 .

 1 Figure 1.

Figure 2 .

 2 Figure 2. Patients undergoing diagnostic coronary angiography (n=2774)

Figure 3 .

 3 Figure 3.

Figure 4 .

 4 Figure 4. Management decision following JCC meetings.

Page 10 of 29 International Journal of Clinical Practice International Journal of Clinical Practice

	19.7%, p=0.43; two vessel disease 30.4% v 29.5%, p=0.911; impaired left ventricular
	function 34.5% v 38.0%, p=0.704 (figure 3b).
	Following case discussion at the pre-VDL JCC and post-VDL JCC meetings patient
	management decisions were as follows: medical management 15.8% v 18.8%, p=0.15;
	PCI 36.8% v 17.2%, p=0.001; surgical revascularisation 21.1% v 48.4%, p<0.001; other
	o F 26.3% v 21.4%, p=0.09 (figure
	r
	P
	e e r
	R e v i e w
	O n
	l y

ACKNOWLEDGEMENTS

The study was supported by an unrestricted research grant from Lifestream Medical Systems Ltd.

International Journal of Clinical Practice

International Journal of Clinical Practice

AUTHOR CONTRIBUTIONS

RA Veasey -conception and design and analysis and interpretation of data and drafting of the manuscript.


MD Panagiotis ; Anagnostis
email: anagnwstis.pan@yahoo.gr

Despina Selalmatzidou

Stergios A Polyzos

Athanasios Panagiotou

Aristidis Slavakis

Aikaterini Panagiotidou

Vasilios G Athyros

Asterios Karagiannis

Dimitri P Mikhailidis

Marina Kita

Comparative effects of rosuvastatin and atorvastatin on glucose metabolism and adipokine levels in non-diabetic patients with dyslipidaemia: a prospective randomized open-label study

Keywords: rosuvastatin, atorvastatin, glucose, adiponectin, leptin

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

• Conflicting data exist regarding the impact of statins on glucose metabolism, insulin resistance and adipokine levels

• The JUPITER trial has raised concern about the risk for new onset diabetes mellitus (NODM) following statin therapy, an issue that was also addressed by a recent metaanalysis, which reported a 9% increased risk in NODM, especially for older participants

What's new?

• This is the first study showing a beneficial effect of rosuvastatin on insulin resistance in non-diabetic patients with dyslipidaemia, compared with atorvastatin at equivalent dosage, in contrast to previous reports • The effect of both statins on fasting glucose and HbA 1c levels was neutral

• Treatment with both statins had no impact on adiponectin and leptin levels compared with baseline.

Introduction

Conflicting data exist regarding the impact of statins on glucose metabolism, insulin resistance (IR) and adipokines [START_REF] Athyros | Should adipokines be considered in the choice of the treatment of obesity-related health problems?[END_REF][START_REF] Polyzos | Nonalcoholic fatty liver disease: the pathogenetic roles of insulin resistance and adipocytokines[END_REF]. Statins might increase the risk for new onset diabetes mellitus (NODM) [START_REF] Ridker | Rosuvastatin to prevent vascular events in men and women with elevated C-reactive protein[END_REF][START_REF] Sattar | Statins and risk of incident diabetes: a collaborative meta-analysis of randomised statin trials[END_REF], although small studies evaluating their effect on insulin sensitivity (IS) reported conflicting results [START_REF] Her | Effects of atorvastatin 20 mg, rosuvastatin 10 mg, and atorvastatin/ezetimibe 5 mg/5 mg on lipoproteins and glucose metabolism[END_REF][START_REF] Park | Comparative study of low doses of rosuvastatin and atorvastatin on lipid and glycemic control in patients with metabolic syndrome and hypercholesterolemia[END_REF][START_REF] Ando | Effects of atorvastatin and pravastatin on glucose tolerance, adipokine levels and inflammatory markers in hypercholesterolaemic patients[END_REF][START_REF] Kaya | Comparison of the effects of atorvastatin and simvastatin in women with polycystic ovary syndrome: A prospective, randomized study[END_REF][START_REF] Koh | Differential metabolic effects of pravastatin and simvastatin in hypercholesterolemic patients[END_REF].

We evaluated the effect of rosuvastatin and atorvastatin on glucose metabolism, IS, leptin, adiponectin and high-sensitivity C-reactive protein (hsCRP) levels in non-diabetic patients with dyslipidaemia, not meeting goals [START_REF] Grundy | Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III guidelines[END_REF] for low-density lipoprotein cholesterol (LDL-C). Hospital (Thessaloniki, Greece), a tertiary referral center. We included patients with dyslipidaemia not meeting goals for LDL-C [START_REF] Grundy | Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III guidelines[END_REF]. Exclusion criteria were: DM, malignancy, thyroid dysfunction, any lipid-lowering or anti-obesity agents. At screening, physical examination and basal laboratory assessment were performed.

Patients and methods

Study design and subjects

Patients were randomly assigned to receive either rosuvastatin 10 mg or atorvastatin 20 mg once daily for 12 weeks. Randomization was performed by Microsoft Excel.

Patients were reassessed at 4 and 12 weeks in terms of adverse events. The statin was discontinued and the subjects were withdrawn from the study in case of drug intolerance, pregnancy, transaminase elevation >3x or creatine kinase >10x upper limit of normal.

All blood samples were obtained between 8:00 and 9:00 am after an overnight fast.

Basal laboratory parameters, serum insulin, leptin and hsCRP levels were assessed at weeks. IS was estimated at the same intervals using the homeostasis model assessment-IR (HOMA-IR) and the quantitative IS check index (QUICKI). HOMA-IR was calculated based on the formula: [fasting serum insulin (µIU/L) x fasting plasma glucose (mmol/L)]/22.5, while QUICKI was based on the logarithmic transformation: 1/[log glucose (mg/dL)+log insulin (µU/mL)] [START_REF] Mojiminiyi | Effect of homeostasis model assessment computational method on the definition and associations of insulin resistance[END_REF][START_REF] Katz | Quantitative insulin sensitivity check index: a simple, accurate method for assessing insulin sensitivity in humans[END_REF]. Insulin was measured using an immunochemiluminometric (ICMA) assay (Immulite 2500, DPC, Los Angeles, USA).

Enzyme-linked immunosorbent assays (ELISA) were used to measure total circulating adiponectin (Biovendor, Heidelberg, Germany) and leptin levels (Mercodia, Uppsala, Sweden). HsCRP was measured by nephelometry (Dade, Behring, BN II, Germany).

Statistical analysis

Data for continuous variables are presented as mean ± standard deviation (SD). Data for categorical variables are presented as numbers and/or percentages. The Kolmogorov-Smirnov test was used to test the normality of distribution of continuous variables.

Repeated measures analysis of variance (ANOVA) was used to test for differences within the levels of continuous variables, in cases of more than 2 serial measurements. Wilcoxon Signed Ranks Test was used to test for differences within the levels of continuous variables, in cases with 2 serial measurements. The independent t-test or Mann-Whitney test was used for between group differences. Pearson's (r) or Spearman's (rs) correlation coefficients were used. A p <0.05 (two-tailed) was considered significant. Statistical analysis was performed using SPSS for Windows version 13 (SPSS Inc., Illinois, USA).

Power analysis was performed with GPower 3.0.8 (University of Kiel, Germany). The 2 groups were comparable at baseline regarding anthropometric parameters including age, gender, weight, blood pressure, body mass index, waist and hip circumference. No significant differences in these parameters were noted after treatment. The 2 groups did not differ in baseline fasting plasma glucose, haemoglobin A 1c (HbA 1c ), insulin, HOMA-IR and QUICKI. No difference was observed in fasting plasma glucose and HbA 1c after treatment within either group (table 1). Compared with baseline, only rosuvastatin caused a significant reduction in insulin and HOMA-IR (p=0.005 and p=0.011, respectively) and a significant increase in QUICKI at 12 weeks (p=0.003) (table 1). These differences were greater with rosuvastatin compared with atorvastatin at 12 weeks [-35% vs +17%, (p = 0.032) for insulin, -33% vs +17% (p = 0.008) for HOMA-IR and +11% vs 6% (p = 0.015) for QUICKI, respectively]. Differences in insulin and HOMA-IR remained significant (p = 0.012 and p = 0.007, respectively) at the end of study after adjustment for age, gender and deltas in waist circumference, adiponectin, leptin and TG. However, differences in QUICKI did not remain significant after similar adjustment. Regarding insulin and HOMA-IR at 12 weeks, the between groups difference remained significant after adjustment for baseline insulin (p=0.043 and p=0.029, respectively) Baseline HOMA-IR did not significantly affect the [START_REF] Katz | Quantitative insulin sensitivity check index: a simple, accurate method for assessing insulin sensitivity in humans[END_REF] We did not perform a priori power analysis, because this is a pilot study. However, a post-hoc power analysis for actual differences of QUICKI regarding the within-between group interaction (repeated measures ANOVA) provided a power of 87% for a type I error probability 0.05.

No differences within the 2 groups were observed regarding the levels of adiponectin, leptin and hsCRP at baseline, 4 and 12 weeks of treatment (table 1).

However, compared with atorvastatin, rosuvastatin significantly increased adiponectin (p = 0.016) and decreased leptin levels (p = 0.009) compared with atorvastatin at 12 weeks.

These differences did not remain significant after adjustment for age, gender and deltas in waist circumference, HOMA-IR, TG and leptin or adiponectin levels, respectively.

Discussion

Our study demonstrates for the first time that rosuvastatin may improve IS in nondiabetic patients compared with atorvastatin. Other comparative studies did not show changes in IR [START_REF] Her | Effects of atorvastatin 20 mg, rosuvastatin 10 mg, and atorvastatin/ezetimibe 5 mg/5 mg on lipoproteins and glucose metabolism[END_REF][START_REF] Park | Comparative study of low doses of rosuvastatin and atorvastatin on lipid and glycemic control in patients with metabolic syndrome and hypercholesterolemia[END_REF]. The 2 statins had neutral impact on HbA 1c in our study with a trend towards reducing fasting plasma glucose levels (mainly with rosuvastatin). It is not clear if the statin-related risk of NODM is a 'class effect' [START_REF] Athyros | Lipid-lowering agents and new onset diabetes mellitus[END_REF][START_REF] Athyros | Preventing Type 2 Diabetes Mellitus: Room for Residual Risk Reduction after Lifestyle Changes?[END_REF]. Furthermore, data from randomized studies have shown that the CVD risk reduction by statins is greater in patients with type 2 DM than in non-diabetics, thus counteracting a potential increase in CVD risk related to NODM [START_REF] Athyros | Lipid-lowering agents and new onset diabetes mellitus[END_REF][START_REF] Athyros | Preventing Type 2 Diabetes Mellitus: Room for Residual Risk Reduction after Lifestyle Changes?[END_REF].

With respect to their impact on IS, previous reports of rosuvastatin showed no effect [START_REF] Ter Avest | Effect of rosuvastatin on insulin sensitivity in patients with familial combined hyperlipidaemia[END_REF][START_REF] Milionis | Starting with rosuvastatin in primary hyperlipidemia--Is there more than lipid lowering?[END_REF][START_REF] Bellia | Early vascular and metabolic effects of rosuvastatin compared with simvastatin in patients with type 2 diabetes[END_REF] or even worsening of IR [START_REF] Kostapanos | Rosuvastatin treatment is associated with an increase in insulin resistance in hyperlipidaemic patients with impaired fasting glucose[END_REF]. Atorvastatin was neutral in our study which is consistent with most previous reports [START_REF] Kaya | Comparison of the effects of atorvastatin and simvastatin in women with polycystic ovary syndrome: A prospective, randomized study[END_REF][START_REF] Chu | Atorvastatin does not affect insulin sensitivity and the adiponectin or leptin levels in hyperlipidemic Type 2 diabetes[END_REF], although some demonstrated amelioration [START_REF] Huptas | Effect of atorvastatin (10 mg/day) on glucose metabolism in patients with the metabolic syndrome[END_REF] or worsening of IR [START_REF] Koh | Atorvastatin causes insulin resistance and increases ambient glycemia in hypercholesterolemic patients[END_REF]. We cannot exclude a dose-dependent effect of statins on IR. We found no change in adipokines after treatment. There are limited data regarding the effects of rosuvastatin on adiponectin and leptin levels. Rosuvastatin [START_REF] Qu | Effect of atorvastatin versus rosuvastatin on levels of serum lipids, inflammatory markers and adiponectin in patients with hypercholesterolemia[END_REF], as well as atorvastatin increase adiponectin levels in patients with dyslipidaemia [START_REF] Arca | Serum adiponectin is decreased in patients with familial combined hyperlipidemia and normolipaemic relatives and is influenced by lipid-lowering treatment[END_REF][START_REF] Hyogo | Efficacy of atorvastatin for the treatment of nonalcoholic steatohepatitis with dyslipidemia[END_REF]. In terms of leptin, conflicting data exist, since atorvastatin reduced plasma leptin levels in diabetic patients [START_REF] Von Eynatten | Adipocytokines as a novel target for the anti-inflammatory effect of atorvastatin in patients with type 2 diabetes[END_REF] but had no effect in patients with dyslipidemia [START_REF] Koh | Atorvastatin causes insulin resistance and increases ambient glycemia in hypercholesterolemic patients[END_REF][START_REF] Hyogo | Efficacy of atorvastatin for the treatment of nonalcoholic steatohepatitis with dyslipidemia[END_REF]. Regarding systemic inflammation, rosuvastatin and atorvastatin have been shown to reduce hsCRP levels [START_REF] Ridker | Rosuvastatin to prevent vascular events in men and women with elevated C-reactive protein[END_REF][START_REF] Arca | Serum adiponectin is decreased in patients with familial combined hyperlipidemia and normolipaemic relatives and is influenced by lipid-lowering treatment[END_REF][START_REF] Von Eynatten | Adipocytokines as a novel target for the anti-inflammatory effect of atorvastatin in patients with type 2 diabetes[END_REF]. The lack of reduction in hsCRP levels in our study may be attributed to the average baseline levels of hsCRP of 3 mg/L or the small number of patients.

One advantage of the present study is that we evaluated the impact of both statins at equivalent doses on IS at 2 intervals (4 and 12 weeks). However, we acknowledge limitations. First, there was unequal distribution between males and females and a nonsignificant difference in mean age of patients (about 5 years older in the atorvastatin group). However, we performed adjustments for several parameters including age and gender. We also acknowledge that HOMA and QUICKI have high variability and should be regarded more as derivatives of the insulin level than as truly reflecting IS. We were not able to perform a trapezoidal/frequently sampled glucose tolerance test (with measurement of insulin) (which would be better) or the euglycaemic clamp (which is the gold standard), but a good and strong correlation between estimates of IR derived from HOMA or QUICKI and from the euglycemic clamp has been reported [START_REF] Wallace | Use and abuse of HOMA modeling[END_REF][START_REF] Sarafidis | Validity and reproducibility of HOMA-IR, 1/HOMA-IR, QUICKI and McAuley's indices in patients with hypertension and type II diabetes[END_REF], despite coefficients of variation (CV) of 24-28% for HOMA-IR, and 4-8% for QUICKI in 1 study [START_REF] Sarafidis | Validity and reproducibility of HOMA-IR, 1/HOMA-IR, QUICKI and McAuley's indices in patients with hypertension and type II diabetes[END_REF][START_REF] Antuna-Puente | HOMA or QUICKI: is it useful to test the reproducibility of formulas?[END_REF]. It should be recognized that HOMA is a measure of basal insulin sensitivity and β-cell function and, in contrast to euglycemic clamp, it does not give information about the stimulated state. QUICKI is actually a logHOMA-IR, displaying an acceptable correlation and having the same limitations with HOMA [START_REF] Wallace | Use and abuse of HOMA modeling[END_REF]. In addition, using log-transforming HOMA by log (glucose x insulin)/log (22.5)

A 12 -

 12 week prospective randomized open-label single-dose study was conducted from April 2009 to May 2010 in the Department of Endocrinology, Hippokration General

  4 and 12 weeks. Total serum adiponectin was assessed at baseline and at 12

  patients completed the study, 18 (3 males/15 females, age 54.7 ± 11.3 years) received rosuvastatin and 18 (3 males/15 females, age 59.8 ± 10.3 years) atorvastatin.

Table 1 . Effects of 4-and 12-week treatment of atorvastatin and rosuvastatin on glucose metabolism, adipokines and systemic inflammation.

 1

	and log-transforming

#: p for within groups comparisons (repeated measures ANOVA or Wilcoxon Signed Ranks Test) *: p<0.05 for between groups comparison (independent T-test or Mann-Whitney test) a: p<0.05 compared to baseline; (Bonferroni post-hoc analysis) Abbreviations: LDL-C: low density lipoprotein cholesterol, HDL-C: high-density lipoprotein cholesterol, HOMA-IR: homeostasis model assessment-insulin resistance, QUICKI: quantitative insulin-sensitivity check index, HbA1c: haemoglobulin A1c, hsCRP: high sensitivity C-reactive protein

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International Journal of Clinical PracticeInternational Journal of Clinical Practice

Conflict of interest

This article was written independently. The authors did not receive financial or professional help with the preparation of the manuscript. The authors have given talks, attended conferences and participated in advisory boards and trials sponsored by various pharmaceutical companies.

Authors' contributions

Concept/design, PA and DS; Data analysis/interpretation, SAP, AP, AS, and AP; Critical revision of article, VGA, AK; Approval of article, MK, DPM.