Acute renal haemodynamic effects of glucagon-like peptide-1 receptor agonist exenatide in healthy overweight men.

AIMS: To determine the acute effect of glucagon-like peptide-1 (GLP-1) receptor agonist exenatide and the involvement of nitric oxide (NO) on renal haemodynamics and tubular function, in healthy overweight men. METHODS: Renal haemodynamics and tubular electrolyte handling were measured in 10 healthy overweight men (aged 20-27 years; BMI 26-31 kg/m(2)) during intravenous administration of placebo (saline 0.9%), exenatide, and exenatide combined with the NO-synthase inhibitor L-N(G)-monomethyl arginine (L-NMMA). Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were determined by inulin and para-aminohippurate clearance techniques, respectively, based on timed urine sampling. Glomerular hydrostatic pressure and vascular resistance of afferent and efferent renal arterioles were calculated using the Gomez formulae. Urinary electrolytes, osmolality and pH were also measured. RESULTS: GFR increased by a mean of 18 ± 20 (+20%; p = 0.021) and ERPF increased by a median (interquartile range) of 68 (26; 197) ml/min/1.73 m(2) (+14%; p = 0.015) during exenatide infusion versus placebo. During L-NMMA infusion, exenatide increased GFR by mean 8 ± 12 ml/min/1.73 m(2) (+9%; p = 0.049). Exenatide increased estimated glomerular pressure by +6% (p = 0.015) and reduced afferent renal vascular resistance by -33% (p = 0.038), whereas these effects were blunted during L-NMMA infusion. Exenatide increased absolute and fractional sodium excretion, urinary osmolality and urinary pH. The tubular effects of exenatide were not altered by concomitant L-NMMA infusion. CONCLUSIONS: Exenatide infusion in healthy overweight men acutely increases GFR, ERPF and glomerular pressure, probably by reducing afferent renal vascular resistance, and at least partially in an NO-dependent manner. As baseline renal haemodynamics in patients with type 2 diabetes differ from those in healthy individuals, clinical studies on the renal effects of GLP-1 receptor agonists are warranted.

Glucagon-like peptide-1 receptor agonist exenatide has no acute effect on MRI-measured exocrine pancreatic function in patients with type 2 diabetes: a randomized trial.

AIMS: To investigate the effect of infusion of the glucagon-like peptide-1 (GLP-1) receptor agonist exenatide on exocrine pancreatic function. METHODS: This was a randomized, placebo-controlled, double-blind, crossover study in 12 male patients with type 2 diabetes, treated with oral glucose-lowering agents. On two separate occasions, exenatide or placebo (saline 0.9%) were administered intravenously, in randomized order. Exocrine pancreatic function was measured using secretin-enhanced magnetic resonance cholangiopancreatography. The primary outcome measure was defined as secretin-stimulated pancreatic excretion volume. Secondary outcome measures were maximum secretion speed and the time to reach this maximum. In addition, changes in pancreatic duct (PD) diameter were measured. RESULTS: Exenatide did not change secretin-stimulated pancreatic excretion volume, as compared with placebo (mean ± standard error of the mean 142.2 ± 15.6 ml vs 142.6 ± 8.5 ml, respectively; p = 0.590). Also, exenatide did not change the maximum secretion speed (33.1 ± 1.4 vs 36.9 ± 2.2; p = 0.221), nor the time to reach this maximum (both 4 min 30 s). No differences in PD diameter were observed between the two groups. CONCLUSIONS: Infusion of exenatide did not directly influence MRI-measured exocrine pancreatic excretion in patients with type 2 diabetes. Although long-term studies are warranted, these findings suggest that potential adverse pancreatic effects of GLP-1 receptor agonists are not mediated by changes in exocrine pancreatic secretion.

Is insulin the most effective injectable antihyperglycaemic therapy?

AIMS: The recent type 2 diabetes American Diabetes Association/European Association for the Study of Diabetes (ADA/EASD) position statement suggested insulin is the most effective glucose-lowering therapy, especially when glycated haemoglobin (HbA1c) is very high. However, randomized studies comparing glucagon-like peptide-1 receptor agonists (GLP-1RAs) exenatide once-weekly [OW; DURATION-3 (Diabetes therapy Utilization: Researching changes in A1c, weight, and other factors Through Intervention with exenatide ONce-Weekly)] and liraglutide once-daily [OD; LEAD-5 (Liraglutide Effect and Action in Diabetes)] with insulin glargine documented greater HbA1c reduction with GLP-1RAs, from baseline HbA1c ∼8.3% (67 mmol/mol). This post hoc analysis of DURATION-3 and LEAD-5 examined changes in HbA1c, fasting glucose and weight with exenatide OW or liraglutide and glargine, by baseline HbA1c quartile. METHODS: Descriptive statistics were provided for change in HbA1c, fasting glucose, weight, and insulin dose, and subjects (%) achieving HbA1c <7.0%, by baseline HbA1c quartile. Inferential statistical analysis on the effect of baseline HbA1c quartile was performed for change in HbA1c. An analysis of covariance (ANCOVA) model was used to evaluate similarity in change in HbA1c across HbA1c quartiles. RESULTS: At 26 weeks, in both studies, HbA1c reduction, and proportion of subjects reaching HbA1c <7.0%, were similar or numerically greater with the GLP-1RAs than glargine for all baseline HbA1c quartiles. Fasting glucose reduction was similar or numerically greater with glargine. Weight decreased with both GLP-1RAs across all quartiles; subjects taking glargine gained weight, more at higher baseline HbA1c. Adverse events were uncommon although gastrointestinal events occurred more frequently with GLP-1RAs. CONCLUSIONS: HbA1c reduction with the GLP-1RAs appears at least equivalent to that with basal insulin, irrespective of baseline HbA1c. This suggests that liraglutide and exenatide OW may be appropriate alternatives to basal insulin in type 2 diabetes, including when baseline HbA1c is very high (≥9.0%).

Brain reward-system activation in response to anticipation and consumption of palatable food is altered by glucagon-like peptide-1 receptor activation in humans.

AIM: To test the hypothesis that food intake reduction after glucagon-like peptide-1 (GLP-1) receptor activation is mediated through brain areas regulating anticipatory and consummatory food reward. METHODS: As part of a larger study, we determined the effects of GLP-1 receptor activation on brain responses to anticipation and receipt of chocolate milk versus a tasteless solution, using functional MRI (fMRI). Obese subjects with type 2 diabetes, and obese and lean subjects with normoglycaemia (n = 48) underwent three fMRI sessions at separate visits with intravenous infusion of the GLP-1 receptor agonist exenatide, exenatide with prior GLP-1 receptor blockade by exendin-9-39 or placebo, during somatostatin pituitary-pancreatic clamps. RESULTS: Body mass index negatively correlated with brain responses to receipt of chocolate milk and positively correlated with anticipation of receipt of chocolate milk in brain areas regulating reward, appetite and motivation. Exenatide increased brain responses to receipt of chocolate milk and decreased anticipation of receipt of chocolate milk compared with placebo, paralleled by reductions in food intake. Exendin-9-39 largely prevented these effects. CONCLUSIONS: Our findings show that GLP-1 receptor activation decreases anticipatory food reward, which may reduce cravings for food and increases consummatory food reward, which may prevent overeating.

Insulin degludec results in lower rates of nocturnal hypoglycaemia and fasting plasma glucose vs. insulin glargine: A meta-analysis of seven clinical trials.

BACKGROUND AND AIMS: Basal insulin analogues have a reduced risk of hypoglycaemia compared with NPH insulin, but hypoglycaemia still remains a major impediment to achieving recommended fasting plasma glucose (FPG) targets in patients with diabetes. Insulin degludec (IDeg) is a new basal insulin that forms soluble multihexamers after subcutaneous injection resulting in an ultra-long duration of action and stable glucose-lowering effect. The aim of this analysis was to compare the effect of IDeg on FPG and nocturnal confirmed hypoglycaemia as compared to insulin glargine (IGlar). METHODS AND RESULTS: Data were included from seven phase 3a, randomised, open-label, treat-to-target clinical trials in which once-daily IDeg was compared with once-daily IGlar. Two trials included a total of 957 patients with type 1 diabetes (T1D) and five trials included a total of 3360 patients with type 2 diabetes (T2D); all trials were 26 or 52 weeks in duration. Confirmed hypoglycaemia was defined as plasma glucose <3.1 mmol/L or severe episodes requiring assistance, and nocturnal hypoglycaemia occurred between 00:01 and 05:59. In all trials, the mean end-of-trial FPG was lower for IDeg than IGlar, reaching statistical significance in three trials. Similarly, IDeg was associated with a lower rate of nocturnal confirmed hypoglycaemia vs. IGlar, which was statistically significant in three trials, regardless of type of diabetes or background therapy. CONCLUSION: This analysis shows that the lower rate of nocturnal confirmed hypoglycaemia seen with IDeg relative to IGlar is accompanied by a reduced mean FPG, in particular in patients with T2D.

Diabetes-specific emotional distress in people with Type 2 diabetes: a comparison between primary and secondary care.

AIMS: To compare levels of diabetes distress in people with Type 2 diabetes treated in primary and secondary care and to examine demographic and clinical correlates that may explain potential differences in levels of distress between care settings. METHODS: People with Type 2 diabetes from 24 primary care practices (n = 774) and three secondary care clinics (n = 526) completed the Problem Areas In Diabetes questionnaire. Data on HbA1c levels and diabetes complications were derived from medical charts. Hierarchical ordinal regression analysis was used to investigate which correlates could explain the potential differences in level of diabetes distress between care settings. RESULTS: Diabetes distress levels and the prevalence of elevated diabetes distress were considerably lower in the participants treated in primary care (mean (SD) total diabetes distress score 8 (11); 4% of participants with a Problem Areas In Diabetes score ≥ 40) than in secondary care (mean (SD) total diabetes distress score 23 (21); 19% of participants with a Problem Areas In Diabetes score ≥ 40, P < 0.001). In addition to care setting, the following variables were also independently related to diabetes distress: younger age, ethnic minority status, using insulin, having a higher HbA1c level, having a higher BMI and the presence of neuropathy. Other diabetes complications were not independently associated with diabetes distress. CONCLUSIONS: In primary care, lower levels of diabetes distress were reported than in secondary care. The difference in diabetes distress between care settings can be largely, but not fully, explained by specific demographic and clinical characteristics. These results need to be interpreted with caution as they are based on two separate studies, but do call into question the need to screen for diabetes distress in people with Type 2 diabetes in primary care.

Sex-specific effects of naturally occurring variants in the dopamine receptor D2 locus on insulin secretion and type 2 diabetes susceptibility.

AIMS: Modulation of dopamine receptor D2 (DRD2) activity affects insulin secretion in both rodents and isolated pancreatic ß-cells. We hypothesized that single nucleotide polymorphisms in the DRD2/ANKK1 locus may affect susceptibility to type 2 diabetes in humans. METHODS: Four potentially functional variants in the coding region of the DRD2/ANKK1 locus (rs1079597, rs6275, rs6277, rs1800497) were genotyped and analysed for type 2 diabetes susceptibility in up to 25 000 people (8148 with type 2 diabetes and 17687 control subjects) from two large independent Dutch cohorts and one Danish cohort. In addition, 340 Dutch subjects underwent a 2-h hyperglycaemic clamp to investigate insulin secretion. Since sexual dimorphic associations related to DRD2 polymorphisms have been previously reported, we also performed a gender-stratified analysis. RESULTS: rs1800497 at the DRD2/ANKK1 locus was associated with a significantly increased risk for type 2 diabetes in women (odds ratio 1.14 (1.06-1.23); P = 4.1*104) but not in men (odds ratio 1.00 (95% CI 0.93-1.07); P = 0.92) or the combined group. Although rs1800497 was not associated with insulin secretion, we did find another single nucleotide polymorphism in this locus, rs6275, to be associated with increased first-phase glucose-stimulated insulin secretion in women (P = 5.5*104) but again not in men (P = 0.34). CONCLUSION: The present data identify DRD2/ANKK1 as a potential sex-specific type 2 diabetes susceptibility gene.

Postprandial microvascular function deteriorates in parallel with gradual worsening of insulin sensitivity and glucose tolerance in men with the metabolic syndrome or type 2 diabetes.

AIMS/HYPOTHESIS: Hyperinsulinaemia-induced whole-body glucose uptake during a euglycaemic-hyperinsulinaemic clamp is partly mediated by increased capillary density. We hypothesised that physiological insulinaemia in response to a mixed meal may also enhance microvascular function, and that this may be impaired in insulin-resistant individuals and patients with type 2 diabetes. METHODS: Twelve men with uncomplicated type 2 diabetes, 13 with metabolic syndrome and 12 age-matched healthy normoglycaemic controls, mean age 57 ± 6 years, underwent skin capillary video microscopy before and 60 and 120 min following a standardised mixed meal to measure baseline capillary density (BCD) and capillary density during post-occlusive peak reactive hyperaemia (PRH), also termed capillary recruitment. Oral glucose insulin sensitivity (Matsuda index) and postprandial hyperglycaemia (2 h AUC(glucose)) were calculated. RESULTS: Fasting BCD was similar among groups, but fasting PRH was lowest in diabetes (p < 0.05). Postprandially, both BCD and PRH increased in all groups (p < 0.001); however, the meal-related increase in BCD was significantly lower in diabetes and metabolic syndrome vs controls (both p < 0.05). At all time points, postprandial PRH was lower in both diabetes and metabolic syndrome vs controls (both p < 0.05). In pooled analysis, postprandial mean PRH correlated with Matsuda index (r = 0.386, p = 0.018) and inversely with 2 h AUC(glucose) (r = -0.336, p = 0.042). CONCLUSIONS/INTERPRETATION: Gradual deterioration in meal-related capillary recruitment was paralleled by decreasing insulin sensitivity and postprandial hyperglycaemia, as assessed in healthy normoglycaemic men, men with the metabolic syndrome and those with type 2 diabetes. These findings suggest that in both impaired glucose tolerance and in overt diabetes microvascular dysfunction might contribute to postprandial dysglycaemia. TRIAL REGISTRATION: ClinicalTrials.gov NCT00721552.

Effects of induced hyperinsulinaemia with and without hyperglycaemia on measures of cardiac vagal control.

AIMS/HYPOTHESIS: We examined the effects of serum insulin levels on vagal control over the heart and tested the hypothesis that higher fasting insulin levels are associated with lower vagal control. We also examined whether experimentally induced increases in insulin by beta cell secretagogues, including glucagon-like peptide-1 (GLP-1), will decrease vagal control. METHODS: Respiration and ECGs were recorded for 130 healthy participants undergoing clamps. Three variables of cardiac vagal effects (the root mean square of successive differences [rMSSD] in the interbeat interval of the heart rate [IBI], heart-rate variability [HRV] caused by peak-valley respiratory sinus arrhythmia [pvRSA], and high-frequency power [HF]) and heart rate (HR) were obtained at seven time points during the clamps, characterised by increasing levels of insulin (achieved by administering insulin plus glucose, glucose only, glucose and GLP-1, and glucose and GLP-1 combined with arginine). RESULTS: Serum insulin level was positively associated with HR at all time points during the clamps except the first-phase hyperglycaemic clamp. Insulin levels were negatively correlated with variables of vagal control, reaching significance for rMSSD and log10HF, but not for pvRSA, during the last four phases of the hyperglycaemic clamp (hyperglycaemic second phase, GLP-1 first and second phases, and arginine). These associations disappeared when adjusted for age, BMI and insulin sensitivity. Administration of the beta cell secretagogues GLP-1 and arginine led to a significant increase in HR, but this was not paired with a significant reduction in HRV measures. CONCLUSION/INTERPRETATION: Experimentally induced hyperinsulinaemia is not correlated with cardiac vagal control or HR when adjusting for age, BMI and insulin sensitivity index. Our findings suggest that exposure to a GLP-1 during hyperglycaemia leads to a small acute increase in HR but not to an acute decrease in cardiac vagal control.

Extra-pancreatic effects of incretin-based therapies: potential benefit for cardiovascular-risk management in type 2 diabetes.

Development of cardiovascular disease is one of the major complications of type 2 diabetes mellitus (T2DM). The chronic hyperglycaemic state is often accompanied by dyslipidaemia, hypertension, low-grade systemic inflammation and oxidative stress which collectively result in a high risk of micro- and macrovascular complications. Current glucose-lowering agents do not sufficiently address fore-mentioned macrovascular-risk factors. Recently, new therapeutic agents were introduced, based on the incretin hormone glucagon-like peptide-1 (GLP-1), that is, the GLP-1 receptor agonists (GLP-1RA) and dipeptidyl-peptidase 4 (DPP-4) inhibitors. Beside its effect on pancreatic insulin secretion, GLP-1 exerts several extra-pancreatic effects such as slowing down gastric emptying, promoting satiety and reducing food intake and weight loss. Also, GLP-1 and GLP-1RA were shown to improve cardiovascular-risk profiles, by reducing body fat content, blood pressure, circulating lipids and inflammatory markers in patients with T2DM. This review summarizes the presently known evidence with regard to extra-pancreatic effects of the incretin-based agents, focusing on the actions that improve the cardiovascular-risk profile. We present available data from clinical trials of at least 24 week duration, but also findings from small-sized clinical 'proof of principle' studies. We conclude that GLP-1 RA and to a lesser extent DPP-4 inhibitors are promising agents with regard to their effects on body weight, blood pressure and lipids, which collectively ameliorate the cardiovascular-risk profile and as such may have added value in the treatment of T2DM. However, large-sized long-term outcome studies are warranted to show the true added value of these agents in the treatment of patients with T2DM.

Lowering of postprandial lipids in individuals with type 2 diabetes treated with alogliptin and/or pioglitazone: a randomised double-blind placebo-controlled study.

AIMS/HYPOTHESIS: Pharmacological augmentation of glucagon-like peptide 1 receptor signalling by dipeptidyl peptidase 4 (DPP-4) inhibition reduced intestinal lipoprotein secretion in experimental studies, suggesting that DPP-4 inhibitors may ameliorate dyslipidaemia and thus reduce cardiovascular risk in patients with type 2 diabetes. We assessed the effects of alogliptin (Alo) and Alo co-administered with pioglitazone (Pio) vs placebo (Pbo) on triacylglycerol (TG)-rich lipoproteins in type 2 diabetes before and following a high-fat meal. METHODS: Seventy-one patients (age 18-70 years), who did not reach HbA(1c) 6.5% (48 mmol/mol) with lifestyle and/or metformin, sulfonylurea or glinide therapy, participated in this 16 week, double-centre (university hospitals) Pbo-controlled parallel-group study. All participants, people doing measurements or examinations, and people assessing the outcomes were blinded to group assignment. Fasting TG 1.7-5.0 mmol/l was among the entry criteria. Patients received a high-fat mixed meal before and 4 and 16 weeks after randomisation (allocation by central office) to Alo (n = 25), Alo/Pio (n = 22) or Pbo (n = 24). Blood was sampled at pre-specified intervals, starting at 15 min before and ending 8 h after meal ingestion. RESULTS: At week 16, Alo (n = 25) and Alo/Pio (n = 21) vs Pbo (n = 24) produced similar significant reductions in total postprandial TG response (incremental AUC [iAUC]; p < 0.001), as well as in chylomicron TG (p < 0.001) and VLDL1 TG iAUCs (p < 0.001 and p = 0.012, respectively). Postprandial chylomicron apolipoprotein B-48 iAUC showed a significant decrease after Alo treatment (p = 0.028), and a non-significant trend towards a decrease with Alo/Pio (p = 0.213). The incidence of adverse events was low and consistent with previous studies. CONCLUSIONS/INTERPRETATION: Treatment with Alo and Alo/Pio produced significant reductions in postprandial TG and TG-rich lipoproteins, contributing to an improved overall cardiometabolic risk profile in type 2 diabetes. The data support the concept that incretins not only modulate glucose metabolism but also influence chylomicron metabolism in intestinal cells. TRIAL REGISTRATION: ClinicalTrials.gov number NCT00655863.

Impaired insulin sensitivity is accompanied by disturbances in skeletal muscle fatty acid handling in subjects with impaired glucose metabolism.

OBJECTIVE: To determine insulin sensitivity and skeletal muscle fatty acid (FA) handling at baseline and after a high-fat mixed meal in impaired fasting glucose (IFG), impaired glucose tolerance (IGT), IFG/IGT and normal glucose tolerance (NGT) subjects. DESIGN: In this multi-center study, insulin sensitivity and ß-cell function were assessed (n=102), using a euglycemic-hyperinsulinemic and hyperglycemic clamp with additional arginine stimulation and a 75 g oral glucose tolerance test. Fasting and postprandial skeletal muscle FA handling was examined in a substudy using the forearm balance technique (n=35). SUBJECTS: A total of 102 subjects with IFG (n=48), IGT (n=12), IFG/IGT (n=26) and NGT (n=16). RESULTS: IFG, IGT and IFG/IGT subjects had lower insulin sensitivity with no differences between groups, and lower impaired ß-cell function compared with NGT controls. The early postprandial increase in triacylglycerol (TAG) concentration was higher (iAUC(0-2 h) IFG: 238.4±26.5, IGT: 234.0±41.0 and NGT: 82.6±13.8 µmol l(-1) min(-1), both P<0.05) and early TAG extraction was increased (AUC(0-2 h) IFG: 56.8±9.0, IGT: 52.2±12.0 and NGT: 3.8±15.4 nmol·100 ml(-1) min(-1), P<0.05 and P=0.057, respectively) in both IFG and IGT subjects. CONCLUSION: IFG, IGT and IFG/IGT subjects have lower insulin sensitivity and impaired ß-cell function compared with age- and BMI-matched NGT controls. The increased postprandial TAG response and higher muscle TAG extraction in both IFG and IGT compared with NGT may lead to ectopic fat accumulation in the skeletal muscle, thereby contributing to insulin resistance.

Glucocorticoid receptor gene polymorphisms are associated with reduced first-phase glucose-stimulated insulin secretion and disposition index in women, but not in men.

AIM: Glucocorticoids are efficacious anti-inflammatory agents, but, in susceptible individuals, these drugs may induce glucose intolerance and diabetes by affecting ß-cell function and insulin sensitivity. We assessed whether polymorphisms in the glucocorticoid receptor gene NR3C1 associate with measures of ß-cell function and insulin sensitivity derived from hyperglycaemic clamps in subjects with normal or impaired glucose tolerance. METHODS: A cross-sectional cohort study was conducted in four academic medical centres in the Netherlands and Germany. Four hundred and forty-nine volunteers (188 men; 261 women) were recruited with normal glucose tolerance (n=261) and impaired glucose tolerance (n=188). From 2-h hyperglycaemic clamps, first- and second-phase glucose-stimulated insulin secretion, as well as insulin sensitivity index and disposition index, were calculated. All participants were genotyped for the functional NR3C1 polymorphisms N363S (rs6195), BclI (rs41423247), ER22/23EK (rs6189/6190), 9ß A/G (rs6198) and ThtIIII (rs10052957). Associations between these polymorphisms and ß-cell function parameters were assessed. RESULTS: In women, but not in men, the N363S polymorphism was associated with reduced disposition index (P=1.06 10(-4) ). Also only in women, the ER22/23EK polymorphism was associated with reduced first-phase glucose-stimulated insulin secretion (P=0.011) and disposition index (P=0.003). The other single-nucleotide polymorphisms were not associated with ß-cell function. Finally, none of the polymorphisms was related to insulin sensitivity. CONCLUSION: The N363S and ER22/23EK polymorphisms of the NR3C1 gene are negatively associated with parameters of ß-cell function in women, but not in men.

Dipeptidyl peptidase-4 inhibitors and preservation of pancreatic islet-cell function: a critical appraisal of the evidence.

Type 2 diabetes mellitus (T2DM) develops as a consequence of progressive ß-cell dysfunction in the presence of insulin resistance. None of the currently-available T2DM therapies is able to change the course of the disease by halting the relentless decline in pancreatic islet cell function. Recently, dipeptidyl peptidase (DPP)-4 inhibitors, or incretin enhancers, have been introduced in the treatment of T2DM. This class of glucose-lowering agents enhances endogenous glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) levels by blocking the incretin-degrading enzyme DPP-4. DPP-4 inhibitors may restore the deranged islet-cell balance in T2DM, by stimulating meal-related insulin secretion and by decreasing postprandial glucagon levels. Moreover, in rodent studies, DPP-4 inhibitors demonstrated beneficial effects on (functional) ß-cell mass and pancreatic insulin content. Studies in humans with T2DM have indicated improvement of islet-cell function, both in the fasted state and under postprandial conditions and these beneficial effects were sustained in studies with a duration up to 2 years. However, there is at present no evidence in humans to suggest that DPP-4 inhibitors have durable effects on ß-cell function after cessation of therapy. Long-term, large-sized trials using an active blood glucose lowering comparator followed by a sufficiently long washout period after discontinuation of the study drug are needed to assess whether DPP-4 inhibitors may durably preserve pancreatic islet-cell function in patients with T2DM.

GLP-1 based therapies: differential effects on fasting and postprandial glucose.

Glucagon-like peptide-1 (GLP-1), a gut-derived hormone secreted in response to nutrients, has several glucose and weight regulating actions including enhancement of glucose-stimulated insulin secretion, suppression of glucagon secretion, slowing of gastric emptying and reduction in food intake. Because of these multiple effects, the GLP-1 receptor system has become an attractive target for type 2 diabetes therapies. However, GLP-1 has significant limitations as a therapeutic due to its rapid degradation (plasma half-life of 1-2 min) by dipeptidyl peptidase-4 (DPP-4). Two main classes of GLP-1-mediated therapies are now in use: DPP-4 inhibitors that reduce the degradation of GLP-1 and DPP-4-resistant GLP-1 receptor (GLP-1R) agonists. The GLP-1R agonists can be further divided into short- and long-acting formulations which have differential effects on their mechanisms of action, ultimately resulting in differential effects on their fasting and postprandial glucose lowering potential. This review summarizes the similarities and differences among DPP-4 inhibitors, short-acting GLP-1R agonists and long-acting GLP-1R agonists. We propose that these different GLP-1-mediated therapies are all necessary tools for the treatment of type 2 diabetes and that the choice of which one to use should depend on the specific needs of the patient. This is analogous to the current use of modern insulins, as short-, intermediate- and long-acting versions are all used to optimize the 24-h plasma glucose profile as needed. Given that GLP-1-mediated therapies have advantages over insulins in terms of hypoglycaemic risk and weight gain, optimized use of these compounds could represent a significant paradigm shift for the treatment of type 2 diabetes.

Does interference with the renin-angiotensin system protect against diabetes? Evidence and mechanisms.

Agents interfering with the renin-angiotensin system (RAS) were consistently shown to lower the incidence of type 2 diabetes mellitus (T2DM), as compared to other antihypertensive drugs, in hypertensive high-risk populations. The mechanisms underlying this protective effect of RAS blockade using angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers on glucose metabolism are not fully understood. In this article, we will review the evidence from randomized controlled trials and discuss the proposed mechanisms as to how RAS interference may delay the onset of T2DM. In particular, as T2DM is characterized by ß-cell dysfunction and obesity-related insulin resistance, we address the mechanisms that underlie RAS blockade-induced improvement in ß-cell function and insulin sensitivity.

Clinical relevance of anti-exenatide antibodies: safety, efficacy and cross-reactivity with long-term treatment.

AIMS: Antibody formation to therapeutic peptides is common. This analysis characterizes the time-course and cross-reactivity of anti-exenatide antibodies and potential effects on efficacy and safety. METHODS: Data from intent-to-treat patients in 12 controlled (n = 2225,12-52 weeks) and 5 uncontrolled (n = 1538, up to 3 years) exenatide twice-daily (BID) trials and 4 controlled (n = 653,24-30 weeks) exenatide once weekly (QW) trials with 1 uncontrolled period (n = 128,52 weeks) were analysed. RESULTS: Mean titres peaked early (6-22 weeks) and subsequently declined. At 30 weeks, 36.7% of exenatide BID patients were antibody-positive; 31.7% exhibited low titres (≤125) and 5.0% had higher titres (≥625). Antibody incidence declined to 16.9% (1.4% higher titre) at 3 years. Similarly, 56.8% of exenatide QW patients were antibody-positive (45.0% low/11.8% higher titre) at 24-30 weeks, declining to 45.4% positive (9.2% higher titre) at 52 weeks. Treatment-emergent anti-exenatide antibodies from a subset of patients tested did not cross-react with human GLP-1 or glucagon. Other than injection-site reactions, adverse event rates in antibody-positive and antibody-negative patients were similar. Efficacy was robust in both antibody-negative and antibody-positive patients (mean HbA1c change: -1.0 and -0.9%, respectively, exenatide BID; -1.6% and -1.3% exenatide QW). No correlation between change in HbA1c and titre was observed for exenatide BID, although mean reductions were attenuated in the small subset of patients (5%) with higher titres. A significant correlation was observed for exenatide QW with no difference between antibody-negative and low-titre patients, but an attenuated mean reduction in the subset of patients (12%) with higher titres. CONCLUSIONS: Low-titre anti-exenatide antibodies were common with exenatide treatment (32% exenatide BID, 45% exenatide QW patients), but had no apparent effect on efficacy. Higher-titre antibodies were less common (5% exenatide BID, 12% exenatide QW) and within that titre group, increasing antibody titre was associated with reduced average efficacy that was statistically significant for exenatide QW. Other than injection-site reactions, anti-exenatide antibodies did not impact the safety of exenatide.

The longitudinal association between glycaemic control and health-related quality of life following insulin therapy optimisation in type 2 diabetes patients. A prospective observational study in secondary care.

PURPOSE: To test whether improvement in glycosylated haemoglobin (HbA(1c)) as a marker of glycaemic control, following intensifying insulin therapy, is associated with improvements in HRQoL. METHODS: Dutch sub-optimally controlled (HbA(1c) > 7%) type 2 diabetes patients (N = 447, mean age 59 ± 11) initiated insulin glargine therapy. Data were collected at baseline, 3 and 6 months, and included HbA(1c) and measures of HRQoL: diabetes symptom distress (Diabetes Symptom Checklist-revised; DSC-r), fear of hypoglycaemia (Hypoglycaemia Fear Survey; HFS-w) and emotional well-being (WHO-5 wellbeing index). RESULTS: HbA(1c) decreased from 8.8 ± 1.4% to 8.0 ± 1.2% and 7.7 ± 1.3% at 3 and 6 months follow-up, respectively (P < 0.001), DSC-r score improved from 17.7 ± 14.7 to 14.3 ± 13.3 and 13.6 ± 13.3 (P < 0.001). HFS-w score did not significantly change. WHO-5 score increased from 56 ± 23 to 62 ± 23 and 65 ± 22 P < 0.001). A modest, significant association was found between HbA(1c) and WHO-5 score (B = -1.8, 95% CI: -2.7 to -0.8) and HbA1c and DSC-r score (B = 1.0, 95% CI: 0.4 to 1.6). No such association was found for HFS-w score. CONCLUSIONS: An association between improvement in HbA(1c) by means of optimising insulin therapy and improvement in HRQoL in type 2 diabetes patients has been observed. A weak, yet significant longitudinal association was found between improved HbA(1c) and emotional well-being and diabetes symptom distress.

Low-dose glucocorticoid treatment affects multiple aspects of intermediary metabolism in healthy humans: a randomised controlled trial.

AIM/HYPOTHESIS: To assess whether low-dose glucocorticoid treatment induces adverse metabolic effects, as is evident for high glucocorticoid doses. METHODS: In a randomised placebo-controlled double-blind (participants and the investigators who performed the studies and assessed the outcomes were blinded) dose-response intervention study, 32 healthy men (age 22 ± 3 years; BMI 22.4 ± 1.7 kg/m(2)) were allocated to prednisolone 7.5 mg once daily (n = 12), prednisolone 30 mg once daily (n = 12), or placebo (n = 8) for 2 weeks using block randomisation. Main outcome measures were glucose, lipid and protein metabolism, measured by stable isotopes, before and at 2 weeks of treatment, in the fasted state and during a two-step hyperinsulinaemic clamp conducted in the Clinical Research Unit of the Academic Medical Centre, Amsterdam, the Netherlands RESULTS: Prednisolone, compared with placebo, dose dependently and significantly increased fasting plasma glucose levels, whereas only prednisolone 30 mg increased fasting insulin levels (29 ± 15 pmol/l). Prednisolone 7.5 mg and prednisolone 30 mg decreased the ability of insulin to suppress endogenous glucose production (by 17 ± 6% and 46 ± 7%, respectively, vs placebo). Peripheral glucose uptake was not reduced by prednisolone 7.5 mg, but was decreased by prednisolone 30 mg by 34 ± 6% (p < 0.0001). Compared with placebo, prednisolone treatment tended to decrease lipolysis in the fasted state (p = 0.062), but both prednisolone 7.5 mg and prednisolone 30 mg decreased insulin-mediated suppression of lipolysis by 11 ± 5% and 34 ± 6%, respectively. Finally, prednisolone treatment increased whole-body proteolysis during hyperinsulinaemia, which tended to be driven by prednisolone 30 mg (5 ± 2%; p = 0.06). No side effects were reported by the study participants. All participants completed the study and were analysed. CONCLUSIONS/INTERPRETATION: Not only at high doses but also at low doses, glucocorticoid therapy impaired intermediary metabolism by interfering with the metabolic actions of insulin on liver and adipose tissue. These data indicate that even low-dose glucocorticoids may impair glucose tolerance when administered chronically. TRIAL REGISTRATION: ISRCTN83991850.