Role of glucotoxicity and lipotoxicity in the pathophysiology of Type 2 diabetes mellitus and emerging treatment strategies

Type 2 diabetes mellitus is a disease characterized by persistent and progressive deterioration of glucose tolerance. Both insulin resistance and impaired insulin secretion contribute to development of Type 2 diabetes. However, whilst insulin resistance is fully apparent in the pre-diabetic condition, impairment of insulin secretion worsens over the time, being paralleled by a progressive decline in both pancreatic B-cell function and B-cell mass. Intense research has identified a number of genetic variants that may predispose to impaired B-cell function, but such predisposition can be precipitated and worsened by toxic effects of hyperglycaemia (glucotoxicity) and elevated levels of free fatty acids (lipotoxicity). All these aspects of the pathogenesis of Type 2 diabetes are discussed in this review. Moreover, treatments that target reduction in glucotoxicity or lipotoxicity are outlined, including emerging strategies that target the role of glucagon-like peptide 1 and sodium glucose co-transporter 2.

Lower fasting blood glucose, glucose variability and nocturnal hypoglycaemia with glargine vs NPH basal insulin in subjects with Type 1 diabetes

BACKGROUND AND AIMS

To compare switching from NPH insulin (NPH) to insulin glargine (glargine) with continuing NPH for changes in fasting blood glucose (FBG) in patients with Type 1 diabetes on basal-bolus therapy with insulin lispro as bolus insulin. Secondary objectives included self-monitoring blood glucose, mean daily blood glucose (MDBG) and mean amplitude glucose excursion (MAGE) values alongside changes in HbA(1c) and safety profiles.

METHODS AND RESULTS

This was a 30-week, parallel, open-label, multicentre study. Seven-point profiles were used to calculate MDBG and MAGE. Hypoglycaemia and adverse events were recorded by participants. FBG improved significantly with both glargine (baseline-endpoint change: -28.0 mg/dL; 95% CI: -37.3, -18.7 mg/dL; p<0.001) and NPH (-9.8 mg/dL; 95% CI: -19.1, -0.5 mg/dL; p=0.0374). The improvement was significantly greater with glargine than NPH (mean difference: -18.2 mg/dL; 95% CI: -31.3, -5.2 mg/dL; p=0.0064). MDBG (-10.1 mg/dL; 95% CI: -18.1, -2.1 mg/dL; p=0.0126) and MAGE (-20.0 mg/dL; 95% CI: -34.5, -5.9 mg/dL; p=0.0056) decreased significantly with glargine, but not NPH although endpoint values were no different with the two insulins. Baseline to endpoint change in HbA(1c) was similar (-0.56 vs -0.56%) with no differences at endpoint. Overall hypoglycaemia was no different, but glargine reduced nocturnal hypoglycaemia ("serious episodes" with BG < 42 mg/dl, p=0.006) whereas NPH did not (p=0.123), although endpoint values were no different.

CONCLUSION

Switching from NPH to glargine is well tolerated and results into lower FBG, and lower glucose variability while reducing nocturnal hypoglycaemia. These data provide a rationale for more aggressive titration to target with glargine in Type 1 diabetes.

Megatrials in type 2 diabetes. From excitement to frustration?

Whether glycaemic control may result in a reduction of cardiovascular (CV) risk has been a matter of continuous discussion and investigation. Epidemiological analyses have extensively suggested a relationship between glycaemic control and CV events; however, the results of intervention trials have been less conclusive. The UKPDS reported a 16% reduction in the risk of myocardial infarction, but this reduction was not statistically significant. The results of the Kumamoto and PROactive studies could not allow any firm conclusions to be drawn either, because of limited size and the defined primary endpoint, respectively. The results of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) and Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trials and the Veteran Administration Diabetes Trial (VADT) were published in rapid succession over the second half of 2008 and at the beginning of 2009. A total number of almost 25,000 type 2 diabetic patients were recruited in these three trials, which assessed the effect of intensive glycaemic control vs conventional treatment on well-defined CV endpoints. In spite of the achievement and maintenance of strict glycaemic control (HbA(1c) <7.0%), no beneficial effect of intensive therapy was apparent in any of the studies. At the same time these results were presented, the results of an analysis of the 10 year follow-up of the UKPDS also became available and provided a more optimistic view of the potential benefit of achieving good glycaemic control. The relative risk reductions for myocardial infarction and all-cause mortality were significantly lower in the patients who initially received the intensive treatment compared with those in the conventional treatment arm. Moreover, the initial benefit in terms of microvascular complications observed at the end of the intervention trial remained unaltered at follow-up. Once again the debate on the importance of glycaemic control in preventing macrovascular complications remains unsettled. These results, however, require some reconciliation, and the objective of this commentary is to analyse a series of elements, including the changes in the treatment approach to CV risk factors in type 2 diabetes, the effect of glucose-lowering agents, and the characteristics of the patients included in the different trials, that should be taken into account when interpreting the results of intervention trials in type 2 diabetes.

Dysglycaemia in non-diabetic hypertensive patients: comparison of the impact of two different classifications of impaired fasting glucose on the cardiovascular risk profile

The clinical correlates and risk profile of prediabetes (fasting plasma glucose (FPG) values in the upper normal limits but below the diabetic threshold) in hypertension, an insulin-resistant, prodiabetogenic condition, are scarcely known. For this reason, we evaluated 982 non-diabetic (FPG,<126 mg 100 ml(-1) and no antidiabetic treatment) referred hypertensive patients without a history of cardiovascular disease grouped by mild (100-109 mg 100 ml(-1)) and advanced (110-125 mg 100 ml(-1)) dysglycaemia compared with normal FPG (<100 mg 100 ml(-1)). FPG, total and high density lipoprotein (HDL) cholesterol, triglycerides and total white blood cell count were assessed by standard methodologies; 10-year predicted coronary heart disease (CHD) risk was approximated by the Framingham risk score (FRS). Metabolic syndrome (MetS) was diagnosed by standard categorical criteria using either 110 or 100 mg 100 ml(-1) as a threshold for impaired fasting glucose (IFG). FPG was above 110 in 13% and between 100 and 109 in 20% of patients. In both dysglycaemic groups, perturbed glucose homeostasis was associated with abnormally high fasting triglycerides, low HDL cholesterol, obesity, worse CHD risk profile and higher white blood cell count. MetS was highly prevalent and its distribution pattern was markedly influenced by the definitions of IFG based on different FPG cutoffs. Thus, even mildly perturbed glucose homeostasis associates with atherogenic dyslipidaemia, obesity and adverse risk profile in non-diabetic hypertensive patients. Because of its prediabetic nature, dysglycaemia should prompt measures to prevent new-onset diabetes, although the role of IFG as an independent risk factor awaits specifically designed intervention trials.

The metabolic syndrome is related to albuminuria in Type 2 diabetes

AIMS

To determine the relationships between metabolic syndrome (MetS), diabetic nephropathy (DN) and renal function in Type 2 diabetes.

METHODS

In a clinic-based cohort of 1314 Type 2 diabetic patients (58% male; age 62 +/- 10 years), we analysed MetS, detected DN and estimated glomerular filtration rate (eGFR).

RESULTS

Prevalence of both microalbuminuria and macroalbuminuria were higher in subjects with MetS than in those without. Prevalence of DN (microalbuminuria and macroalbuminuria) increased with the number of MetS components. eGFR was lower in subjects with MetS than in those without (87 +/- 23 vs. 92 +/- 20 ml/min per 1.73 m2; P < 0.001). The lowest eGFR values were found in those with four or more components of the MetS. Prevalence of low eGFR increased with the stage of DN and was affected by MetS only in normoalbuminuric patients. MetS was independently associated with DN, also after adjustment for confounders [odds ratio (OR) 2.82, confidence interval (CI) 1.93, 4.11] and the presence of low eGFR in the model (OR 2.74, CI 1.87, 4.01). Similarly, MetS was a predictor of low eGFR (OR 1.93, CI 1.11, 3.36), but after adjustment for DN, the association was lost. Finally, MetS per se was independently associated with DN, but not with low eGFR after adjustment for all of the individual components of the MetS.

CONCLUSIONS

This study suggests a close and independent association between MetS and renal impairment. However, it is unclear whether and to what extent treating MetS by an intensive multifactorial therapeutic approach will prevent or delay progression to renal failure.

Beta-cell apoptosis in type 2 diabetes: quantitative and functional consequences

Type 2 diabetes, the most common form of diabetes in humans, is characterized by impaired insulin secretion paralleled by a progressive decline in beta-cell function and chronic insulin resistance. Several authors have showed that in type 2 diabetes there is a reduction of islet and/or insulin-containing cell mass or volume. Regulation of the beta-cell mass appears to involve a balance of beta-cell replication and apoptosis but, at the molecular level, pancreatic beta-cell loss by apoptosis appears to play an important role in the development of insulin deficiency and the onset and/or progression of the disease. The mechanisms favoring apoptosis in type 2 diabetic pancreatic islets and new potential therapeutic approaches to prevent beta-cell death and maintain beta-cell mass are discussed.

The effect of the availability of inhaled insulin on glycaemic control in patients with Type 2 diabetes failing on oral therapy: the evaluation of Exubera as a therapeutic option on insulin initiation and improvement in glycaemic control in clinical practice (EXPERIENCE) trial

AIM

To examine the impact of inhaled human insulin (Exubera, EXU) on patient or physician willingness to adopt insulin after oral glucose-lowering agent failure.

METHODS

During a randomized controlled trial in primary, secondary and tertiary care in Europe and North America, 739 patients using >or= 2 oral glucose-lowering agents with glycated haemoglobin (HbA(1c)) >or= 8.0% were assigned to two treatment groups: Group 1 (standard care with the option of EXU) or Group 2 (standard care only). Standard care included adjusting oral therapy (optimizing current regimen or adding/omitting agents) and/or initiating subcutaneous (s.c.) insulin. The primary endpoint was difference in HbA(1c) between randomized groups at 26 weeks. Secondary outcomes included differences in the rate of uptake of insulin therapy, proportion achieving satisfactory glycaemic control, treatment satisfaction and safety outcomes.

RESULTS

At baseline, insulin was initiated by more [odds ratio 6.0; 95% confidence interval (CI) 4.2 to 8.8; P < 0.0001] patients in Group 1 (86.2%; 76.7% EXU plus 9.5% s.c.) than Group 2 (50.7%; s.c. insulin only). At 26 weeks, mean (sd) changes in HbA(1c) from baseline were -2.0% (1.2%) and -1.7% (1.3%) in Groups 1 and 2, respectively, a difference of -0.2% (95% CI: -0.1% to -0.4%; P = 0.004). In Group 1, 45% of patients achieved an HbA(1c)<or= 7.0% by 26 weeks compared with 39% in Group 2 (P = 0.02).

CONCLUSION

The availability of EXU may increase initiation of insulin, thereby contributing to improved overall glycaemic control in patients with Type 2 diabetes inadequately controlled on two or more oral glucose-lowering agents.

Effects of exendin-4 on islets from type 2 diabetes patients

Exendin-4 is a dipeptidyl peptidase IV (DPP-IV)-resistant glucagon-like peptide 1 (GLP-1) mimetic and its synthetic counterpart, exenatide, is being used in the therapy of type 2 diabetes (T2DM). No information, however, is currently available as for the direct action of exendin-4 on human T2DM islets. In the present study, we exposed pancreatic islets prepared from non-diabetic and T2DM subjects to exendin-4 for 48 h and found that the compound had several, direct beneficial actions on insulin secretion and the expression of genes involved in beta-cell function and differentiation.

Epigenetic regulation of PPARGC1A in human type 2 diabetic islets and effect on insulin secretion

AIMS/HYPOTHESIS

Insulin secretion in pancreatic islets is dependent upon mitochondrial function and production of ATP. The transcriptional coactivator peroxisome proliferator activated receptor gamma coactivator-1 alpha (protein PGC-1alpha; gene PPARGC1A) is a master regulator of mitochondrial genes and its expression is decreased and related to impaired oxidative phosphorylation in muscle from patients with type 2 diabetes. Whether it plays a similar role in human pancreatic islets is not known. We therefore investigated if PPARGC1A expression is altered in islets from patients with type 2 diabetes and whether this expression is influenced by genetic (PPARGC1A Gly482Ser polymorphism) and epigenetic (DNA methylation) factors. We also tested if experimental downregulation of PPARGC1A expression in human islets influenced insulin secretion.

METHODS

The PPARGC1A Gly482Ser polymorphism was genotyped in human pancreatic islets from 48 non-diabetic and 12 type 2 diabetic multi-organ donors and related to PPARGC1A mRNA expression. DNA methylation of the PPARGC1A promoter was analysed in pancreatic islets from ten type 2 diabetic and nine control donors. Isolated human islets were transfected with PPARGC1A silencing RNA (siRNA).

RESULTS

PPARGC1A mRNA expression was reduced by 90% (p<0.005) and correlated with the reduction in insulin secretion in islets from patients with type 2 diabetes. After downregulation of PPARGC1A expression in human islets by siRNA, insulin secretion was reduced by 41% (p <or= 0. 01). We were able to ascribe reduced PPARGC1A expression in islets to both genetic and epigenetic factors, i.e. a common PPARGC1A Gly482Ser polymorphism was associated with reduced PPARGC1A mRNA expression (p<0.00005) and reduced insulin secretion (p<0.05). In support of an epigenetic influence, the PPARGC1A gene promoter showed a twofold increase in DNA methylation in diabetic islets compared with non-diabetic islets (p<0.04).

CONCLUSIONS/INTERPRETATION

We have shown for the first time that PPARGC1A might be important in human islet insulin secretion and that expression of PPARGC1A in human islets can be regulated by both genetic and epigenetic factors.

In Type 1 diabetic patients with good glycaemic control, blood glucose variability is lower during continuous subcutaneous insulin infusion than during multiple daily injections with insulin glargine

AIMS

The superiority of continuous subcutaneous insulin infusion (CSII) over multiple daily injections (MDI) with glargine is uncertain. In this randomized cross-over study, we compared CSII and MDI with glargine in patients with Type 1 diabetes well controlled with CSII. The primary end-point was glucose variability.

METHODS

Thirty-nine patients [38.1 +/- 9.3 years old (mean +/- sd), diabetes duration 16.6 +/- 8.2 years, glycated haemoglobin (HbA(1c)) 7.6 +/- 0.8%], already on CSII for at least 6 months, were randomly assigned to CSII with lispro or MDI with lispro and glargine. After 4 months they were switched to the alternative treatment. During the last month of each treatment blood glucose variability was analysed using glucose standard deviation, mean amplitude of glycaemic excursions (MAGE), lability index and average daily risk range (ADRR). As secondary end-points we analysed blood glucose profile, HbA(1c), number of episodes of hypo- and hyperglycaemia, lipid profile, free fatty acids (FFA), growth hormone and treatment satisfaction.

RESULTS

During CSII, glucose variability was 5-12% lower than during MDI with glargine. The difference was significant only before breakfast considering glucose standard deviation (P = 0.011), significant overall using MAGE (P = 0.016) and lability index (P = 0.005) and not significant using ADRR. Although HbA(1c) was similar during both treatments, during CSII blood glucose levels were significantly lower, hyperglycaemic episodes were fewer, daily insulin dose was less, FFA were lower and treatment satisfaction was greater than during MDI with glargine. The frequency of hypoglycaemic episodes was similar during both treatments.

CONCLUSIONS

During CSII, glucose variability is lower, glycaemic control better and treatment satisfaction higher than during MDI with glargine.

Improving glucose management: ten steps to get more patients with type 2 diabetes to glycaemic goal. Recommendations from the Global Partnership for Effective Diabetes Management

Despite increasingly stringent clinical practice guidelines for glycaemic control, the implementation of recommendations has been disappointing, with over 60% of patients not reaching recommended glycaemic goals. As a result, current management of glycaemia falls significantly short of accepted treatment goals. The Global Partnership for Effective Diabetes Management has identified a number of major barriers that can prevent individuals from achieving their glycaemic targets. This article proposes 10 key practical recommendations to aid healthcare providers in overcoming these barriers and to enable a greater proportion of patients to achieve glycaemic goals. These include advice on targeting the underlying pathophysiology of type 2 diabetes, treating early and effectively with combination therapies, adopting a holistic, multidisciplinary approach and improving patient understanding of type 2 diabetes. Implementation of these recommendations should reduce the risk of diabetes-related complications, improve patient quality of life and impact more effectively on the increasing healthcare cost related to diabetes.

Gestational diabetes, inflammation, and late vascular disease

Physiological changes of pregnancy include insulin resistance and activation of the innate immunity with an inflammatory response. The working hypothesis is that the sub-clinical inflammation associated with excessive adiposity may favor the development of gestational diabetes (GDM) and Type 2 diabetes and other metabolic abnormalities related to cardiovascular disease later in life. In this paper we review the complex interrelationship among inflammatory markers, metabolic syndrome, and endothelium dysfunction in women with GDM and discuss if women with previous GDM (pGDM) could be considered at risk for cardiovascular diseases. MEDLINE was searched for articles relating GDM and the adipokines (tumor necrosis factor-alpha and adiponectin) as well as the acute-phase inflammatory biomarker C-reactive protein that contribute to the development of diabetic pregnancy and vascular complications. However, to date, in pGDM women no prospective study is available, to corroborate the hypothesis that inflammatory pattern could be taken as predictor of cardiovascular disease later in life. Therefore, our paper should provide arguments to perform follow-up programs to prevent cardiovascular events in women with pGDM. Control of body weight, regular physical exercise are indeed powerful intervention tools able at improving insulin sensitivity and reduce sub-clinical inflammation, both involved in the pathogenesis of cardiovascular disease.

Glucose tolerance is negatively associated with circulating progenitor cell levels

AIMS/HYPOTHESIS

Circulating progenitor cells participate in cardiovascular homeostasis. Depletion of the pool of endothelial progenitor cells (EPCs) is associated with increased cardiovascular risk. Furthermore, EPCs are reduced in the presence of classical risk factors for atherosclerotic disease, including diabetes mellitus. This study was designed to evaluate progenitor cell levels in volunteers with different degrees of glucose tolerance.

METHODS

Cardiovascular parameters and the levels of circulating CD34(+) and CD34(+) kinase insert domain receptor (KDR)(+) cells were determined in 219 middle-aged individuals with no pre-diagnosed alterations in carbohydrate metabolism. Glucose tolerance was determined by fasting and 2 h post-challenge glucose levels, with IFG and IGT considered as pre-diabetic states.

RESULTS

CD34(+) and CD34(+)KDR(+) cells were significantly reduced in individuals who were found to have diabetes mellitus, and were negatively correlated with both fasting and post-challenge glucose in the whole population. While only CD34(+) cells, but not CD34(+)KDR(+) cells, were significantly reduced in pre-diabetic individuals, post-challenge glucose was an independent determinant of the levels of both CD34(+) and CD34(+)KDR(+) cells.

CONCLUSIONS/INTERPRETATION

Glucose tolerance was negatively associated with progenitor cell levels in middle-aged healthy individuals. Depletion of endothelial progenitors with increasing fasting and post-meal glucose may be one cause of the high incidence of cardiovascular damage in individuals with pre-diabetes.

Pharmacological intervention in prediabetes: considering the risks and benefits

The impact of the diabetes epidemic will be staggering in terms of costs to individuals and society. Social educational initiatives are imperative to altering the lifestyle trends that drive the growth of the epidemic. Targeted lifestyle or drug interventions aimed at preventing progression from prediabetes to type 2 diabetes mellitus carry costs and risks that need to be considered in the context of expected benefits, which also need to be carefully defined. In terms of pharmacological intervention as part of a primary prevention programme, the risk/benefit assessment must include the potential for adverse effects in a large population of asymptomatic individuals, a significant proportion of whom would not progress to diabetes in the absence of treatment and in whom impaired glucose regulation may reflect different underlying pathogenetic mechanisms. Improving the balance of risks and benefits in drug interventions will require a greater ability to determine which treatments are likely to safely improve glucose regulation and prevent diabetes and its adverse cardiovascular outcomes in individual patients.

Insulin secretion defects of human type 2 diabetic islets are corrected in vitro by a new reactive oxygen species scavenger

Oxidative stress is a putative mechanism leading to beta-cell damage in type 2 diabetes. We studied isolated human pancreatic islets from type 2 diabetic and non-diabetic subjects, matched for age and body mass index. Evidence of increased oxidative stress in diabetic islets was demonstrated by measuring nitrotyrosine concentration and by electron paramagnetic resonance. This was accompanied by reduced glucose-stimulated insulin secretion, as compared to non-diabetic islets (Stimulation Index, SI: 0.9 +/- 0.2 vs. 2.0 +/- 0.4, P<0.01), and by altered expression of insulin (approximately -60%), catalase (approximately +90%) and glutathione peroxidase (approximately +140%). When type 2 diabetic islets were pre-exposed for 24 h to the new antioxidant bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)decandioate di-hydrochloride, nitrotyrosine levels, glucose-stimulated insulin secretion (SI: 1.6+/-0.5) and gene expressions improved/normalized. These results support the concept that oxidative stress may play a role in type 2 diabetes beta-cell dysfunction; furthermore, it is proposed that therapy with antioxidants could be an interesting adjunctive pharmacological approach to the treatment of type 2 diabetes.

Dipeptidyl peptidase 4 (DPP-4) inhibitors and their role in Type 2 diabetes management

Dipeptidyl peptidase 4 (DPP-4) inhibitors are a new pharmacological class of drugs for treating Type 2 diabetes. They improve the capacity of the organism to control glycemia by increasing the levels of active incretins. Their mechanism of action is thus radically different from those of other anti-diabetic drugs currently available. DDP-4 inhibitors use a physiological mechanism to control hyperglycemia, by stimulating the secretion of insulin from beta-cells, decreasing the secretion of glucagon from pancreatic alpha-cells, and at the same time reducing the production of glucose by the liver. DDP-4 inhibitors have shown significant efficacy in maintaining reduced levels of glycosylated hemoglobin for up to 1 year. In vitro and animal studies have shown that they can inhibit apoptosis of beta-cells and favor their regeneration and differentiation. The oral DPP-4 inhibitors vildagliptin, sitagliptin, and saxagliptin are efficacious both alone and in association with other oral anti-diabetic agents and may be administered in a single daily dose. Lastly, they have substantial advantages with respect to other anti-diabetic drugs, since they involve a low risk of hypoglycemia and do not affect body weight.

Dipeptidyl peptidase 4 inhibition and vildagliptin therapy for type 2 diabetes

Dipeptidyl peptidase 4 (DPP-4) inhibition prevents the rapid degradation of the incretins, glucagon-like peptide 1 and glucose-dependent insulinotropic peptide. Incretins have beneficial effects on glycaemic control in patients with type 2 diabetes through their effects on both alpha- and beta-cells in the pancreas and possibly through additional non-pancreatic effects. Vildagliptin is a potent and selective oral DPP-4 inhibitor that has been studied both as monotherapy and in combination with other antidiabetic treatments. This agent has been shown to be well tolerated and is efficacious in reducing glycosylated haemoglobin, fasting plasma glucose and postprandial glucose levels in trials lasting up to 52 weeks. Vildagliptin is weight neutral, does not cause oedema and is associated with a very low incidence of hypoglycaemia. Recently reported clinical data have helped to further clarify the mechanisms of action and effects of vildagliptin. These results suggest that vildagliptin, as a member of the novel class of DPP-4 inhibitors, has the potential to significantly change the clinical management of diabetes. Future research will further define its use in various patient populations and its possible disease-modifying effects.

Evaluation of metalloproteinase 2 and 9 levels and their inhibitors in diabetic and healthy subjects

OBJECTIVES

We hypothesized that molecules active in vascular remodeling (i.e. MMPs and their TIMPs) could be modified in diabetic patients, as indirect markers of the diabetes related generalized abnormality of vascular activity. To test this hypothesis, we measured the plasma levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 in type 2 diabetic patients and in healthy subjects.

METHODS

We enrolled 181 diabetic patients and 165 controls. We measured body mass index (BMI), glycosylated hemoglobin (HbA(1c)), fasting plasma glucose (FPG), fasting plasma insulin (FPI), homeostasis model assessment index (HOMA index), systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), triglycerides (Tg), lipoprotein(a) [Lp(a)], plasminogen activator inhibitor-1 (PAI-1), homocysteine (Hct) fibrinogen (Fg), high sensitivity C-reactive protein (hs-CRP), and plasma levels of MMP-2, MMP-9, TIMP-1, and TIMP-2.

RESULTS

A significant increase (P<0.0001) of BMI, HbA(1c), FPG, FPI, HOMA index, SBP, DBP, TC, LDL-C, Tg, Lp(a), PAI-1, Hct, Fg, and hs-CRP was present in the diabetic group, with a significant decrease (P<0.0001) of HDL-C levels compared to healthy subjects. MMP-2 and MMP-9 levels were significantly higher (P<0.0001) in diabetic patients. Significant TIMP-1, and TIMP-2 increase was also observed (P<0.0001) in the diabetic group.

CONCLUSION

Plasma levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 are increased in diabetic patients which may reflect abnormal extracellular matrix (ECM) metabolism.

Gliclazide protects human islet beta-cells from apoptosis induced by intermittent high glucose

BACKGROUND

Decreased beta-cell mass, mainly due to apoptosis, is crucial for the development and progression of type 2 diabetes. Chronic exposure to high glucose levels is a probable underlying mechanism, whereas the role of oral anti-diabetic agents (sulphonylureas in particular) is still unsettled.

METHODS

To directly investigate more on such issues, we prepared isolated human islets, which were then cultured for 5 days in continuous normal glucose concentration (NG, 5.5 mmol/L) or normal and high (HG, 16.7 mmol/L) glucose levels (alternating every 24 h), with or without the addition of therapeutical concentration (10 micromol L) of gliclazide or glibenclamide.

RESULTS

Intermittent high glucose caused a significant decrease of glucose-stimulated insulin secretion, which was not further affected by either sulphonylurea. Apoptosis, as assessed by electron microscopy, was also significantly increased by alternating high glucose exposure, which was accompanied by altered mitochondria morphology and density volume, and increased concentrations of nitrotyrosine, a marker of oxidative stress. Gliclazide, but not glibenclamide, was able to significantly reduce high glucose induced apoptosis, mitochondrial alterations, and nitrotyrosine concentration increase.

CONCLUSION

Therefore, gliclazide protected human beta-cells from apoptosis induced by intermittent high glucose, and this effect was likely to be due, at least in part, to the anti-oxidant properties of the molecule.

C-reactive protein and metabolic syndrome in women with previous gestational diabetes

BACKGROUND

This study evaluates the presence of metabolic syndrome (MS) and its association with C-reactive protein (CRP) and other cardiovascular (CV) risk factors, in a sample of women with and without previous Gestational Diabetes (pGDM).

METHODS

One hundred and sixty-six women with pGDM and 98 women (controls) with uncomplicated pregnancy were studied 16 months after delivery. In all women, plasma glucose, insulin, lipid profile, serum uric acid, C-reactive protein, fibrinogen and homocysteine were measured. MS was defined according to NCEP ATPIII criteria.

RESULTS

MS was identified in 15 pGDM women (9%) versus 1 control (1%) (p < 0.001). The more frequent metabolic traits were abdominal obesity (36% vs 17%) and low HDL-cholesterol (34% vs 17% in pGDM women and controls, respectively; all p < 0.01). HOMA-R, LDL-cholesterol, fibrinogen, serum uric acid and CRP resulted significantly higher in pGDM women with MS as compared to those without MS after adjustment for BMI. In women with no criteria for MS, only CRP levels were found to be higher in pGDM women compared to controls (p < 0.05). Seventeen percent of pGDM women with no criteria for MS had CRP levels >or=1 mg/L (all controls showed CRP levels <1 mg/L). After a stepwise regression analysis, CRP levels were independently correlated to HOMA-R (r2 = 0.27, p < 0.001) and fibrinogen (r2 = 0.30, p < 0.001).

CONCLUSIONS

In our population, MS occurs in a sizable proportion of pGDM women and is associated with increased levels of CRP, fibrinogen, uric acid and LDL-cholesterol. Moreover, higher levels of CRP, a marker of chronic low-grade inflammation, are present in a subset of women with pGDM, independently of MS.

Pancreas transplant alone has beneficial effects on retinopathy in type 1 diabetic patients

AIMS/HYPOTHESIS

The effects of successful pancreas transplant alone (PTA) on chronic complications of diabetes, in particular diabetic retinopathy, remain disputed. We prospectively studied the course of diabetic retinopathy in PTA recipients and in non-transplanted (non-PTA) type 1 diabetic patients.

METHODS

The PTA and non-PTA groups consisted respectively of 33 (follow-up: 30 +/- 11 months) and 35 patients (follow-up: 28 +/- 10 months). Best corrected visual acuity, slit lamp examination, intraocular pressure measurement, ophthalmoscopy, retinal photographs, and in selected cases angiography were performed. Diabetic retinopathy and its improvement/deterioration were assessed according to criteria proposed by the Eurodiab Study.

RESULTS

At baseline, 9% of PTA and 6% of non-PTA patients had no diabetic retinopathy, 24 and 29% had non-proliferative diabetic retinopathy (NPDR), whereas 67 and 66% had laser-treated and/or proliferative diabetic retinopathy (LT/PDR), respectively. No new case of diabetic retinopathy occurred in either group during follow-up. In the NPDR PTA group, 50% of patients improved by one grading, and 50% showed no change. In the LT/PDR PTA, stabilisation was observed in 86% of cases, whereas worsening of retinopathy occurred in 14% of patients. In the NPDR non-PTA group, diabetic retinopathy improved in 20% of patients, remained unchanged in 10%, and worsened in the remaining 70%. In the LT/PDR non-PTA group, retinopathy did not change in 43% and deteriorated in 57% of patients. Overall, the percentage of patients with improved or stabilised diabetic retinopathy was significantly higher in the PTA group. No differences were found between the two groups with regard to cataract lesions and intraocular pressure values.

CONCLUSIONS/INTERPRETATION

Despite a relatively short follow-up, our study shows that successful PTA can positively affect the course of diabetic retinopathy.