The importance of beta-cell management in type 2 diabetes

Butyrate functions as a histone deacetylase inhibitor to protect pancreatic beta cells from IL-1β-induced dysfunction

Butyrate, a gut microbial metabolite, has beneficial effects on glucose homeostasis and has become an attractive drug candidate for type 2 diabetes (T2D). Recently, we showed that butyrate protects pancreatic beta cells against cytokine-induced dysfunction. In this study, we explored the underlying mechanisms of butyrate action. Pancreatic mouse islets were exposed to a non-cytotoxic concentration of interleukin-1β (IL-1β) for 10 days to mimic low-grade inflammation in T2D. Similar to the effect of butyrate, an isoform-selective histone deacetylase 3 (HDAC3) inhibitor normalized IL-1β-reduced glucose-stimulated insulin secretion and insulin content. In contrast, free fatty acid receptor 2 and 3 (FFAR2/3) agonists failed to normalize IL-1β-induced beta cell dysfunction. Furthermore, butyrate inhibited HDAC activity and increased the acetylation of histone H3 and H4 by 3- and 10-fold, respectively. Genome-wide analysis of histone H3 lysine 27 acetylation (H3K27ac) revealed that butyrate mainly increased H3K27ac at promoter regions (74%), while H3K27ac peaks regulated by IL-1β were more equally distributed at promoters (38%), introns (23%) and intergenic regions (23%). Gene ontology analysis showed that butyrate increased IL-1β-reduced H3K27ac levels near several genes related to hormone secretion and reduced IL-1β-increased H3K27ac levels near genes associated with inflammatory responses. Butyrate alone increased H3K27ac near many genes related to MAPK signaling, hormone secretion, and differentiation, and decreased H3K27ac at genes involved in cell replication. Together, these results suggest that butyrate prevents IL-1β-induced pancreatic islet dysfunction by inhibition of HDACs resulting in changes in H3K27ac levels at genes relevant for beta cell function and inflammatory responses.

The influence of high-density lipoprotein (HDL) and HDL subfractions on insulin secretion and cholesterol efflux in pancreatic derived β-cells

BACKGROUND

High-density lipoprotein (HDL) is considered a complex plasma-circulating particle with subfractions that vary in function, size, and chemical composition. We sought to test the effects of HDL, and HDL subfractions on insulin secretion and cholesterol efflux in the β-cell line MIN-6.

METHODS

We used total HDL and HDL subfractions 2a, 2b, 3a, 3b, and 3c, isolated from human plasma, to test insulin secretion under different glucose concentrations as well as insulin content and cholesterol efflux in the insulinoma MIN-6 cell line.

RESULTS

Incubation of MIN-6 cells with low glucose and total HDL increased insulin release two-fold. Meanwhile, when high glucose and HDL were used, insulin release increased more than five times. HDL subfractions 2a, 2b, 3a, 3b, and 3c elicited higher insulin secretion and cholesterol efflux than their respective controls, at both low and high glucose concentrations. The insulin content of the MIN-6 cells incubated with low glucose and any of the five HDL subclasses had a modest reduction compared with their controls. However, there were no statistically significant differences between each HDL subfraction on their capacity of eliciting insulin secretion, insulin content, or cholesterol efflux.

CONCLUSIONS

HDL can trigger insulin secretion under low, normal, and high glucose conditions. We found that all HDL subfractions exhibit very similar capacity to increase insulin secretion and cholesterol efflux. This is the first report demonstrating that HDL subfractions act both as insulin secretagogues (under low glucose) and insulin secretion enhancers (under high glucose) in the MIN-6 cell line.

Real-world evaluation of Hba1c, blood pressure, and weight loss among patients with type 2 diabetes mellitus treated with canagliflozin: an analysis of electronic medical records from a network of hospitals in Florida

OBJECTIVE

Clinical trials and real-world studies reported that canagliflozin (CANA) improved HbA1c, blood pressure (BP), and weight in patients with type 2 diabetes mellitus (T2DM). This study examines if previous results hold regionally and within specific patient sub-groups.

METHODS

Adults with T2DM and ≥12 months of clinical activity before the first CANA prescription (index) were identified in electronic medical records (January 1, 2012-February 15, 2017) from a network of hospitals in Florida. Quality measures were described at baseline and 3, 6, 9, and 12 months post-index. Selected thresholds were HbA1c < 7%, BP < 140/90 mmHg, and weight loss ≥5%. Sub-groups included patients ≥65 years old, with African American race, with CANA dose increase, initiating CANA in an endocrinology setting, and initiating CANA in a primary care setting.

RESULTS

Overall, 1,259 patients (mean age = 56.7 years; 51.2% female, 70.4% White) were identified. Among patients with a baseline HbA1c ≥ 7%, 16.1% had an HbA1c < 7% 3 months following CANA initiation, and the mean HbA1c decreased from 8.8% to 8.1%. Among patients with a baseline systolic BP ≥140 mmHg or diastolic BP ≥ 90 mmHg, 59.3% attained a systolic BP < 140 mmHg and 77.3% a diastolic BP < 90 mmHg after 3 months. HbA1c and BP responses were sustained through 12 months. The proportion of patients with a weight loss from baseline ≥5% increased from 17.0% at 3 months to 31.1% at 12 months. Consistent trends were observed for all sub-groups.

CONCLUSIONS

In CANA-treated patients and patient sub-groups from a network of Florida hospitals, improvements in quality measures and response durability were similar to clinical trials and other real-world studies.

Apoptosis in pancreatic β-cells is induced by arsenic and atorvastatin in Wistar rats with diabetes mellitus type 2

INTRODUCTION

Diabetes Mellitus type 2 (T2D) is a multifactorial disease. However, it is known that there is an important effect in pancreatic β-cells caused by apoptosis of pro-apoptotic proteins, possibly related to arsenic exposure and atorvastatin treatment.

OBJECTIVE

The goal of this study was to evaluate the effects of atorvastatin treatment on apoptosis of pancreatic β-cells in Wistar rats with induced diabetes type 2 exposed to arsenic.

MATERIAL & METHODS

T2D in Wistar rats was induced by administration of Streptozotocin. The plasmatic glucose concentrations were measured using the glucose oxidase method, and the concentration of glycated hemoglobin (HbA1c) in whole blood was determined. Exposure to arsenic was measured from urine using atomic absorption with hydride generation, and pro-apoptotic proteins in pancreatic β-cells were observed using the Western blotting technique.

RESULTS

Caspase-3 was present in rats that were treated with 10 mg/kg of oral atorvastatin and exposed to 0.01 and 0.025 mg/L of arsenic, but no others proteins were present, such as pro Caspase-8, bcl-2, and Fas. The glycemic levels were 129.2 ± 7.0 mg/dL in the control group and 161.8 ± 14.6 mg/dL and 198.3 ± 18.2 mg/dL (p < .05) in the study groups. HbA1c increased from 2.53% to 3.64% (p < .05) in the control and study groups.

CONCLUSIONS

Atorvastatin treatment and arsenic exposure alone are capable of generating apoptosis in pancreatic β-cells of Wistar rats with T2D. Together, all of these factors induce apoptosis in pancreatic cells.

Achieving the composite endpoint of HbA1c, body weight, and systolic blood pressure reduction with canagliflozin in patients with type 2 diabetes

OBJECTIVE

In addition to achieving glycemic control, weight loss and blood pressure (BP) reduction are important components of type 2 diabetes mellitus (T2DM) management, as many patients with T2DM are overweight/obese and/or have hypertension. Canagliflozin, an SGLT2 inhibitor, has demonstrated improvements in HbA1c, body weight (BW), and systolic BP across a broad range of patients with T2DM. This analysis evaluated achievement of composite endpoints of HbA1c, BW, and systolic BP targets with canagliflozin versus placebo.

METHODS

This post hoc analysis evaluated the proportion of T2DM patients achieving the composite endpoint of HbA1c reduction ≥0.5%, BW reduction ≥3%, and systolic BP reduction ≥4mmHg with canagliflozin 100 and 300mg compared with placebo using pooled data from four 26-week, phase 3 studies (N = 2313; NCT01081834, NCT01106677, NCT01106625, NCT01106690). The proportion of patients achieving the composite endpoint of HbA1c <7.0%, BW reduction ≥3%, and BP <130/80 mmHg was also evaluated.

RESULTS

At week 26, greater proportions of patients met individual HbA1c, BW, and systolic BP targets with canagliflozin versus placebo. A greater proportion of patients treated with canagliflozin 100 or 300 mg versus placebo also achieved the composite endpoint of HbA1c reduction ≥0.5%, BW reduction ≥3%, and systolic BP reduction ≥4 mmHg at week 26 (21.1%, 25.3%, and 5.7%, respectively; odds ratios [95% CI] of 4.5 [3.1, 6.5] and 5.6 [3.8, 8.2]). A greater proportion of patients also achieved the composite endpoint of HbA1c <7.0%, BW reduction ≥3%, and BP <130/80 mmHg with canagliflozin 100 and 300 mg versus placebo (14.7%, 20.9%, and 3.3%, respectively; odds ratios [95% CI] of 5.2 [3.2, 8.4] and 8.4 [5.2, 13.5]). Canagliflozin was generally well tolerated, with a safety profile similar to that seen in other phase 3 studies.

CONCLUSIONS

Patients with T2DM were more likely to achieve clinically important reductions in HbA1c, BW, and systolic BP with canagliflozin versus placebo.

Effects of semaglutide on beta cell function and glycaemic control in participants with type 2 diabetes: a randomised, double-blind, placebo-controlled trial

AIMS/HYPOTHESIS

Semaglutide is a glucagon-like peptide-1 analogue in development for the treatment of type 2 diabetes. Its effects on first- and second-phase insulin secretion and other measures of beta cell function and glycaemic control were assessed.

METHODS

In this single-centre, double-blind, placebo-controlled, parallel-group trial, conducted at the Profil Institut für Stoffwechselforschung, Germany, 75 adult (aged 18-64 years) participants with type 2 diabetes (eligibility: HbA1c of 6.5-9.0% (47.5-74.9 mmol/mol); BMI 20.0-35.0 kg/m2; and treatment with diet and exercise and/or metformin monotherapy with a dose unchanged in the 30 days prior to screening) were randomised (1:1) to once-weekly s.c. semaglutide 1.0 mg (0.25, 0.5, 1.0 mg escalated) or placebo for 12 weeks. Co-primary endpoints were changes from baseline to end of treatment in the first (AUC0-10 min) and second (AUC10-120 min) insulin secretion phases, as measured by the IVGTT. An arginine stimulation test (AST) and a 24 h meal stimulation test were also conducted. A graded glucose infusion test (GGIT) assessed insulin secretion rate (ISR) in treated participants and a group of untreated healthy participants. Safety endpoints were also assessed.

RESULTS

In total, 37 participants received semaglutide and 38 received placebo. Following IVGTT, for insulin, both AUC0-10min and AUC10-120min were significantly increased with semaglutide (estimated treatment ratio [95% CI] 3.02 [2.53, 3.60] and 2.10 [1.86, 2.37], respectively; p < 0.0001). The 24 h meal test showed reduced fasting, postprandial and overall (AUC0-24h) glucose and glucagon responses with semaglutide (p < 0.0001). The AST showed that maximal insulin capacity increased following semaglutide treatment. During GGIT, semaglutide significantly increased ISR to levels similar to those in healthy participants. Semaglutide was well tolerated.

CONCLUSIONS/INTERPRETATION

Twelve weeks of once-weekly treatment with semaglutide significantly improved beta cell function and glycaemic control in participants with type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02212067 FUNDING: The study was funded by Novo Nordisk A/S.

Prevalence of diabetes mellitus after extra corporeal shock wave lithotripsy in 15 years follow-up

Objective:

To investigate the hypothesis that extracorporeal shock wave lithotripsy (ESWL) increases the risk of new onset diabetes mellitus (DM) or significant changes in fasting blood sugar (FBS).

Materials and Methods:

A total number of 307 patients enrolled in this study. All of them had undergone ESWL for kidney stone from 1991 to 1994. In 2009, after 15-19 years, we invited patients to check their blood sugar.

Results:

There were 307 patients, 19.8% females, and 80.1% males. The mean age of the patients was 44 for females and 42 years for males. 47.5% had kidney stone in the left side, 42.9% in the right side and 9.4% bilateral. The mean FBS increasing was 11.86 g/dl. It was 14.54 g/dl for the right side, 8.57 g/dl for left and 16.24 g/dl for bilateral ESWL.

Discussions:

The increasing of FBS is more significant in shock wave intensities higher than 15.5 KV. And there wasn't any significant relationship between age, sex, body mass index (BMI) and total number of shock waves with increasing of FBS. ESWL treatment might associate with increasing FBS without any relation to age, sex and BMI.

Achievement of treatment goals with canagliflozin in patients with type 2 diabetes mellitus: a pooled analysis of randomized controlled trials

OBJECTIVE

To evaluate attainment of diabetes-related treatment goals with canagliflozin, a sodium glucose co-transporter 2 inhibitor, versus placebo in patients with type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

Data were pooled from four 26-week, placebo-controlled, Phase 3 studies of patients with T2DM (N = 2313). Goal attainment with canagliflozin 100 and 300 mg versus placebo was evaluated in the overall population, and in subgroups based on age and sex, at baseline and Week 26.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT01081834, NCT01106677, NCT01106625, NCT01106690.

MAIN OUTCOME MEASURES

Proportion of patients achieving hemoglobin A1C (A1C) < 7.0% and ≤ 6.5%, systolic blood pressure (SBP) < 140 and < 130 mmHg, diastolic blood pressure (DBP) < 90 and < 80 mmHg, low-density lipoprotein cholesterol (LDL-C) < 100 mg/dL (2.6 mmol/L), high-density lipoprotein cholesterol (HDL-C) ≥ 40 mg/dL (1.0 mmol/L), and the composite endpoint of A1C < 7.0%, BP < 130/80 mmHg, and LDL-C <100 mg/dL (2.6 mmol/L) at baseline and Week 26, and proportion with body weight reduction ≥ 5% at Week 26.

RESULTS

At baseline, similar proportions of patients met diabetes-related treatment goals across groups. At Week 26, a greater proportion of patients achieved A1C, SBP, DBP, and HDL-C goals with canagliflozin 100 and 300 mg compared with placebo. More patients achieved body weight reduction of ≥ 5% with canagliflozin 100 and 300 mg versus placebo at Week 26. Fewer patients had LDL-C < 100 mg/dL (2.6 mmol/L) at Week 26 with canagliflozin 100 and 300 mg versus placebo. Canagliflozin 100 and 300 mg also provided better attainment of the composite endpoint of A1C <7.0%, BP < 130/80 mmHg, and LDL-C < 100 mg/dL (2.6 mmol/L) compared with placebo. Attainment of diabetes-related treatment goals was generally similar regardless of age and sex. Key limitations of this analysis include the selection of specific treatment targets that may not be reflective of all patient experiences, the non-prespecified, post hoc nature of the analysis, and the short duration of studies included in the pooled population.

CONCLUSION

Canagliflozin was associated with better attainment of diabetes-related treatment goals compared with placebo, and was generally well tolerated at 26 weeks.

Efficacy and safety of canagliflozin by baseline HbA1c and known duration of type 2 diabetes mellitus

AIMS

Canagliflozin, a sodium glucose co-transporter 2 inhibitor, has demonstrated glycemic improvements across studies of patients with type 2 diabetes mellitus (T2DM). The impact of canagliflozin on HbA1c lowering was assessed by baseline HbA1c and known duration of T2DM.

METHODS

This post hoc analysis pooled data from patients with T2DM enrolled in four 26-week, placebo-controlled, Phase 3 studies of canagliflozin (N=2313). Change in HbA1c from baseline to Week 26 was assessed in the overall population and in subgroups by baseline HbA1c (<8.0%, 8.0%-<9.0%, and ≥9.0%) and known duration of T2DM (<5 years, 5-<10 years, and ≥10 years).

RESULTS

Relative to placebo, canagliflozin 100 and 300 mg provided greater HbA1c reductions in the overall population. Progressively larger placebo-subtracted reductions in HbA1c with canagliflozin 100 and 300 mg were seen with increasing baseline HbA1c. HbA1c reductions were similar across subgroups based on known duration of T2DM. Both canagliflozin doses were generally well tolerated across subgroups, with a safety and tolerability profile consistent with that seen in Phase 3 studies.

CONCLUSIONS

Canagliflozin provided glycemic improvements in patients with T2DM across a range of baseline HbA1c and known duration of T2DM.

Impact of three oral antidiabetic drugs on markers of β-cell function in patients with type 2 diabetes: a meta-analysis

Background

The effect of metformin, pioglitazone and sitagliptin on β-cell function in the treatment of type 2 diabetes is controversial. Therefore, we performed a systematic review and meta-analysis to obtain a better understanding in the β-cell effects of metformin, pioglitazone and sitagliptin.

Methods

We searched Pubmed and the Cochrane Center Register of Controlled Trials to identify relevant studies. Trials investigating effects of sitagliptin, metformin or pioglitazone on β-cell function were identified. The primary outcomes were homeostasis model assessment of β-cells (HOMA-β) and proinsulin/insulin ratio (PI/IR). Secondary outcome was hemoglobin A1c level. We used version 2 of the Comprehensive Meta Analysis software for all statistical analyses.

Results

Metformin monotherapy was more effective than sitagliptin in improving HOMA-β (18.01% (95% CI 11.09% to 24.94%) vs. 11.29% (95% CI 9.21% to 13.37%), P = 0.040) and more effective (−0.137 (95% CI −0.082 to −0.192)) than both sitagliptin (−0.064 (95% CI −0.036 to −0.092), P = 0.019) and pioglitazone (−0.068 (95% CI −0.044 to −0.093), P = 0.015) in decreasing PI/IR. Metformin and sitagliptin combined (40.23% (95%CI 32.30% to 48.16%)) were more effective than sitagliptin and pioglitazone (11.82% (95% CI 6.61% to 17.04%), P = 0.000) and pioglitazone and metformin(9.81% (95% CI 1.67% to 17.95%), P = 0.022) in improving HOMA-β and decreasing PI/IR (−0.177 (95% CI −0.118 to −0.237); −0.080 (95% CI −0.045 to −0.114), P = 0.007; −0.038 (95% CI, −0.005 to 0.071), P = 0.023).

Limitations

The included RCTs were of short duration (12–54 weeks). We could not determine long term effects on β-cells.

Conclusions

Metformin improves β-cell function more effectively than pioglitazone or sitagliptin in type 2 diabetes patients. Metformin and sitagliptin improved HOMA-β and PI/IR more than other combinations.

Imaging beta-cell mass and function in situ and in vivo

Glucose-stimulated insulin secretion (GSIS) from pancreatic beta-cells is critical to the maintenance of blood glucose homeostasis in animals. Both decrease in pancreatic beta-cell mass and defects in beta-cell function contribute to the onset of diabetes, although the underlying mechanisms remain largely unknown. Molecular imaging techniques can help beta-cell study in a number of ways. High-resolution fluorescence imaging techniques provide novel insights into the fundamental mechanisms underlying GSIS in isolated beta-cells or in situ in pancreatic islets, and dynamic changes of beta-cell mass and function can be noninvasively monitored in vivo by imaging techniques such as positron emission tomography and single-photon emission computed tomography. All these techniques will contribute to the better understanding of the progression of diabetes and the search for the optimized therapeutic measures that reverse deficits in beta-cell mass and function.

Stimulation of insulin secretion by large-dose oral arginine administration in healthy adults

The effects of large-dose oral arginine administration on the secretion of insulin by islet β-cells in healthy adults were determined. Eight non-obese healthy volunteers with normal glucose tolerance participated randomly in tests with four stages (with an interval of at least 3 days): the 300 ml purified water stage (PWS), the 75 g glucose stage (GSS), the 30 g arginine stage (ARS) and the 75 g glucose with 30 g arginine stage (GAS). Venous blood samples were collected to detect the concentrations of glucose and insulin at baseline (0) and at 15, 30, 45, 60 and 120 min after drug administration. The glucose and insulin levels were steady in the PWS. The remaining three stages had similarly shaped insulin concentration-time curves, which differed from that of the PWS. The peak concentration of blood insulin and the net incremental area under the curve of blood insulin in the GSS, ARS and GAS were significantly higher compared with those in the PWS (P<0.05). In the ARS, the glucose levels remained stable; however, the net incremental area under the curve for blood insulin in the ARS was much lower compared with that in the GSS or GAS (P<0.05). Large-dose oral arginine administration may slightly stimulate insulin secretion by islet β-cells in healthy adults with normal glucose tolerance in a manner that is independent of glucose concentration.

Efficacy and safety of canagliflozin monotherapy in subjects with type 2 diabetes mellitus inadequately controlled with diet and exercise

AIMS

Canagliflozin is a sodium glucose co-transporter 2 inhibitor in development for type 2 diabetes mellitus (T2DM). The efficacy and safety of canagliflozin were evaluated in subjects with T2DM inadequately controlled with diet and exercise.

METHODS

In this 26-week, randomized, double-blind, placebo-controlled, phase 3 trial, subjects (N = 584) received canagliflozin 100 or 300 mg or placebo once daily. Primary endpoint was the change from baseline in haemoglobin A1c (HbA1c) at week 26. Secondary endpoints included the proportion of subjects achieving HbA1c < 7.0%; change from baseline in fasting plasma glucose (FPG), 2-h postprandial glucose (PPG) and systolic blood pressure (BP); and percent change in body weight, high-density lipoprotein cholesterol (HDL-C) and triglycerides. Adverse events (AEs) were recorded throughout the study.

RESULTS

At week 26, HbA1c was significantly reduced from baseline with canagliflozin 100 and 300 mg compared with placebo (-0.77, -1.03 and 0.14%, respectively; p < 0.001 for both). Both canagliflozin doses significantly decreased FPG, 2-h PPG, body weight and systolic BP (p < 0.001 for all), and increased HDL-C compared with placebo (p < 0.01 for both). Overall incidences of AEs were modestly higher with canagliflozin versus placebo; rates of serious AEs and AE-related discontinuations were low and similar across groups. Incidences of genital mycotic infections, urinary tract infections and osmotic diuresis-related AEs were higher with canagliflozin; these led to few discontinuations. The incidence of hypoglycaemia was low across groups.

CONCLUSION

Canagliflozin treatment improved glycaemic control, reduced body weight and was generally well tolerated in subjects with T2DM inadequately controlled with diet and exercise.

Imeglimin, a novel glimin oral antidiabetic, exhibits a good efficacy and safety profile in type 2 diabetic patients

AIMS

Imeglimin is the first in a new tetrahydrotriazine-containing class of oral antidiabetic agents, the glimins. It has been shown to act on the liver, muscle and pancreatic β-cells to uniquely target the key defects of type 2 diabetes. Two studies were performed to compare the safety and efficacy of imeglimin with metformin and placebo on glycaemic control in type 2 diabetes patients.

METHODS

In a 4-week phase IIa, three-arm parallel group study, patients were randomized to imeglimin 2000 mg once daily (od), imeglimin 1000 mg twice daily (bid) or metformin 850 mg bid and responses to an oral glucose tolerance test (OGTT) were measured. In an 8-week phase IIa, four-arm controlled multi-centre study, patients were randomized to imeglimin 500 mg bid, imeglimin 1500 mg bid, metformin 850 mg bid or placebo. Glycaemic assessments included area under the curve (AUC) up to 6 h (AUC(0-6h)) for glucose during a prolonged meal, fasting plasma glucose (FPG) and HbA1c. Safety and tolerability were assessed in both studies through adverse event recording and laboratory parameters, vital signs and electrocardiogram.

RESULTS

Imeglimin was found to be as effective as metformin at reducing the AUC(PG) and AUC(0-6h) , FPG and HbA1c. Imeglimin exhibited a favourable tolerability profile in comparison to metformin.

CONCLUSIONS

The results from both studies confirm that imeglimin displays a superior benefit : risk profile compared with metformin in type 2 diabetes patients. The encouraging tolerability profile of imeglimin could make it suitable for combination with other classes of antidiabetic agents and may increase availability to a wider patient population.

Early and intensive therapy for management of hyperglycemia and cardiovascular risk factors in patients with type 2 diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) results in significant morbidity and mortality. Results of recent randomized controlled trials demonstrated the ability of early and intensive therapy to reduce the risk of microvascular complications. However, controversy surrounds the ability of such therapy to reduce the risk for macrovascular complications.

OBJECTIVES

This article reviews results from recent clinical trials in patients with T2DM as well as extended follow-up of earlier trials to determine if early, intensive, and individualized therapy aimed at the underlying pathogenesis of the disease could decrease the risk for long-term complications, including cardiovascular disease (CVD).

METHODS

Information was obtained by a search of the PUBMED and EMBASE databases using the search terms type 2 diabetes mellitus, glycosylated hemoglobin, pathophysiology of type 2 diabetes, glycemic control, early intervention, multifactorial intervention, cardiovascular disease, β-cell function, and antidiabetes therapy for the period between 1995 and 2010. Articles dealing with outcomes trials, impact of therapy on microvascular and macrovascular complications, effects of therapeutic agents on the pathophysiology of T2DM, and the impact of agents on CV risk factors were then preferentially selected for in-depth review.

RESULTS

Large-scale clinical trials in patients with T2DM, although largely negative at 5 years for macrovascular end points, suggested benefit for patients with a shorter duration of T2DM (ie, <10 years) and still supported a treatment strategy of early, intensive, and individualized therapy to prevent long-term complications of the disease. In Steno-2, after 13 years of follow-up, early, intensive, multifactorial therapy was associated with a 56% lower risk of all-cause death (P = 0.02) and a 57% lower risk of death from CVD (P = 0.04). In the 10-year follow-up to the United Kingdom Prospective Diabetes Study, intensive therapy was associated with a significant 15% reduction in the risk of myocardial infarction (P = 0.01) and a significant 13% reduction in the risk of death from any cause (P = 0.007). Therapy should be aimed at correcting underlying pathophysiologic defects, including β-cell failure and insulin resistance, and should also correct underlying risk factors for CVD whenever possible.

CONCLUSIONS

Early and intensive antidiabetes treatment was recommended in patients with T2DM, particularly those with a shorter duration of disease and without a history of CVD. The goal was to safely lower glycosylated hemoglobin to <7%, therefore providing beneficial effects on the risk for complications. Hypoglycemia should be avoided. In addition, less aggressive treatment might be suitable for older patients with longstanding diabetes and a history of CVD events. Clinical trial results also provided support for a second important aspect of individualized treatment for patients with T2DM-multifactorial intervention aimed at controlling CVD risk factors.

Thiazolidinediones and cardiovascular risk - a question of balance

BACKGROUND

Several recent meta-analyses of adverse event data from randomized controlled trials with rosiglitazone reveal a possible association between this thiazolidinedione and an increased risk of ischemic myocardial events. This has led to debate on the overall clinical benefit of glitazone therapy for type 2 diabetes. Pioglitazone, on the other hand, has the most extensive cardiovascular outcomes database of all current glucose-lowering therapies, including a large prospective randomized controlled trial designed specifically to assess cardiovascular outcomes (PROactive). The available data suggest that pioglitazone is associated with a reduction in macrovascular risk.

AIMS

In this review, we highlight some of the key factors that need to be considered when assessing the net clinical benefit of thiazolidinediones, focussing on both class effects and those specific to either rosiglitazone or pioglitazone.

RESULTS

For pioglitazone there appears to be no increase in the risk of overall macrovascular events and no adverse clinical consequences of developing signs of heart failure. Furthermore, there is good evidence of significant benefit regarding the composite of death, MI or stroke.

CONCLUSION

The benefits seen with pioglitazone appear to outweigh the risks.

Defining and achieving treatment success in patients with type 2 diabetes mellitus

Traditionally, successful treatment of patients with type 2 diabetes mellitus (DM) has been defined strictly by achievement of targeted glycemic control, primarily using a stepped-care approach that begins with changes in lifestyle combined with oral therapy that is slowly intensified as disease progression advances and β-cell function declines. However, stepped care is often adjusted without regard to the mechanism of hyperglycemia or without long-term objectives. A more comprehensive definition of treatment success in patients with type 2 DM should include slowing or stopping disease progression and optimizing the reduction of all risk factors associated with microvascular and macrovascular disease complications. To achieve these broader goals, it is important to diagnose diabetes earlier in the disease course and to consider use of more aggressive combination therapy much earlier with agents that have the potential to slow or halt the progressive β-cell dysfunction and loss characteristic of type 2 DM. A new paradigm for managing patients with type 2 DM should address the concomitant risk factors and morbidities of obesity, hypertension, and dyslipidemia with equal or occasionally even greater aggressiveness than for hyperglycemia. The use of antidiabetes agents that may favorably address cardiovascular risk factors should be considered more strongly in treatment algorithms, although no pharmacological therapy is likely to be ultimately successful without concomitant synergistic lifestyle changes. Newer incretin-based therapies, such as glucagon-like peptide 1 receptor agonists and dipeptidyl peptidase 4 inhibitors, which appear to have a favorable cardiovascular safety profile as well as the mechanistic possibility for a favorable cardiovascular risk impact, are suitable for earlier inclusion as part of combination regimens aimed at achieving comprehensive treatment success in patients with type 2 DM.

The effects of glucagon-like peptide-1 on the beta cell

Type 2 diabetes is a progressive disease characterized by insulin resistance and impaired beta-cell function. Treatments that prevent further beta-cell decline are therefore essential for the management of type 2 diabetes. Glucagon-like peptide-1 (GLP-1) is an incretin hormone that is known to stimulate glucose-dependent insulin secretion. Furthermore, GLP-1 appears to have multiple positive effects on beta cells. However, GLP-1 is rapidly degraded by dipeptidyl peptidase-4 (DPP-4), which limits the clinical relevance of GLP-1 for the treatment of type 2 diabetes. Two main classes of GLP-1-based therapies have now been developed: DPP-4 inhibitors and GLP-1 receptor agonists. Liraglutide and exenatide are examples of GLP-1 receptor agonists that have been developed to mimic the insulinotropic characteristics of endogenous GLP-1. Both have demonstrated improved beta-cell function in patients with type 2 diabetes, as assessed by homoeostasis model assessment-B analysis and proinsulin : insulin ratio. Additionally, liraglutide and exenatide are able to enhance first- and second-phase insulin secretion and are able to restore beta-cell sensitivity to glucose. Preclinical studies have shown that both liraglutide and exenatide treatment can increase beta-cell mass, stimulate beta-cell proliferation, increase beta-cell neogenesis and inhibit beta-cell apoptosis. Clinical studies are needed to confirm these findings in humans. Replication of these data in humans could have important clinical implications for the treatment of type 2 diabetes.

Fate of the beta-cell in the pathophysiology of type 2 diabetes

OBJECTIVE

To describe the progression of beta-cell dysfunction, now presumed to be the primary progenitor of type 2 diabetes, which appears early in the clinical course (perhaps antedating and even contributing to the development of insulin resistance) and progressively worsens even under treatment.

DATA SOURCES

Medline search of all relevant clinical and review articles.

STUDY SELECTION

By the author.

DATA EXTRACTION

By the author.

DATA SYNTHESIS

The physiology of glucose homeostasis requires the close cooperation of a number of organ systems, humoral secretions, and neural signaling complexes; disruption of any of these processes may lead to the development of type 2 diabetes. Predisposing risk factors for type 2 diabetes include overweight and obesity, poor diet, and lack of exercise. Genetic factors, many of which as yet require elucidation, may also elevate the risk of developing type 2 diabetes. Insulin resistance (IR) has long been recognized as a primary, if not the primary, cause of type 2 diabetes. Recent research in disease pathogenesis suggests that IR is neither a necessary nor sufficient condition for development and progression of type 2 diabetes. Although IR is highly correlated with type 2 diabetes, many individuals with IR will not go on to develop the disease; and the disease may be present in individuals not markedly insulin resistant. The primary progenitor of type 2 diabetes is now presumed to be progressive beta-cell dysfunction, which appears early in the clinical course (perhaps antedating and even contributing to the development of IR) and progressively worsens even under treatment. Among the mechanisms of beta-cell dysfunction in type 2 diabetes is the reduction or abrogation of the "incretin effect."

CONCLUSION

The incretins are gut hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), which in healthy individuals potentiate glucose-dependent insulin secretion. In addition, these hormones, and particularly GLP-1, have a number of protective effects on the beta-cell, including reduction in apoptosis and promotion of beta-cell proliferation and neogenesis. As these benefits are lost in diabetes, "repairing" the incretin effect has become an important treatment target. Treatments that maintain the beta-cell could offer durable glycemic control and potentially reduce the micro- and macrovascular complications associated with type 2 diabetes.

What are the practical implications for treating diabetes in light of recent evidence? Updated recommendations from the Global Partnership for Effective Diabetes Management

The Global Partnership for Effective Diabetes Management was established in 2004 to provide practical guidance to improving glycaemic control for people with type 2 diabetes. Those recommendations have been updated to take account of recent trials assessing the effects of intensive glucose control. We continue to emphasis the importance of early and sustained glycaemic control, aiming for HbA( 1c) 6.5-7% wherever safe and appropriate. Individualisation of targets and the management process is strongly encouraged to accommodate patient circumstances and to avoid hypoglycaemia. Prompt introduction of combinations of agents is suggested when monotherapy is inadequate.Treatments will preferably address the underlying pathophysiology of type 2 diabetes and integrate within a wider programme of care which also aims to reduce modifiable cardiovascular risk factors and better equip patients in the self-management of their condition.

Impact of sitagliptin on markers of beta-cell function: a meta-analysis

BACKGROUND

Progressive beta-cell dysfunction and beta-cell failure are fundamental pathogenic consequences of type 2 diabetes. Dipeptidyl peptidase-IV inhibitors may exhibit improvement on preclinical measures of both beta-cell function, homeostasis model assessment of beta-cell (HOMA-beta) index, and beta-cell dysfunction, proinsulin/insulin ratio (PI/IR), correlating to beta-cell survival.

RESEARCH DESIGN AND METHODS

A systematic literature search through July 2008 was conducted to extract a consensus of randomized, controlled trials of sitagliptin therapy on measures of beta-cell function. A random-effects model meta-analysis evaluated effects on HOMA-beta and PI/IR versus placebo. Several subgroup analyses, including active control, were conducted. Studies were included if they met the following criteria: (1) randomized trials on sitagliptin; (2) placebo or active control; and (3) data reported on HOMA-beta or PI/IR.

RESULTS

A total of 11 trials (n = 3039) reported effects on HOMA-beta and 8 trials (n = 2325) on PI/IR versus placebo. Four trials (n = 1425) were included in the active control subgroup analysis. Sitagliptin significantly improved HOMA-beta index by 12.03% [95% confidence interval (CI), 9.45-14.60] versus placebo. Sitagliptin also significantly decreased PI/IR -0.06 (95% CI, -0.08 to -0.04). Sitagliptin was inferior to active control for HOMA-beta index [5.64% (95% CI, 0.38-10.90)], but not different in terms of PI/IR [0.01 (95% CI, -0.04 to 0.06)].

CONCLUSIONS

Despite significant improvement in HOMA-beta index and PI/IR from placebo, there does not seem to be a benefit of dipeptidyl peptidase-IV inhibitors over other agents with respect to beta-cell function/activity. Long-term prevention of beta-cell dysfunction cannot be ruled out.

Treatment of 46 cats with porcine lente insulin – a prospective, multicentre study

This prospective, multicentre, non-blinded, open study followed 46 cats with diabetes mellitus during treatment with porcine lente insulin (also known as porcine insulin zinc suspension, Caninsulin®, Intervet) for 16±1 weeks (stabilization phase), with additional monitoring of some cats ( n=23) for a variable period. At least three of the following were present at initial presentation: appropriate history of clinical signs consistent with diabetes mellitus, glucosuria, blood glucose greater than 15 mmol/l and fructosamine greater than 380 μmol/l. Insulin treatment was started at a dose rate of 0.25–0.5 IU/kg body weight twice daily, with a maximum starting dose of 2 IU/injection. Twenty-eight of the cats were classed as reaching clinical stability during the study, in 23 of these cats this was during the stabilization phase. Seven cats went into remission during the stabilization phase and one of the cats in week 56. Clinical signs of hypoglycaemia, significantly associated with a dose of 3 units or 0.5 IU/kg or more per cat (twice daily), were observed in nine of the 46 cats during the stabilization phase and concomitant biochemical hypoglycaemia was recorded in most cases. Biochemical hypoglycaemia, recorded in 6% of the blood glucose curves performed during the stabilization phase, was significantly associated with a dose rate of 0.75 IU/kg or more twice daily. This further highlights the need for cautious stepwise changes in insulin dose. The protocol used in the present study is suitable for and easy to use in practice. This study confirmed the efficacy and safety of porcine lente insulin (Caninsulin®) in diabetic cats under field conditions.