Diabesity: therapeutic options

A pathogenic relationship exists between type 2 diabetes and obesity. Over the last decade, the escalation in diabetes cases has paralleled the rapid increase in obesity rates, constituting a global health crisis. Environmental risk factors attributed to the global increase in obesity include the consumption of high‐calorie, high‐fat foods and inadequate physical activity. Obese individuals may also have a genetic predisposition for obesity. Both diabetes and obesity confer an elevated risk of developing a range of complications and comorbidities, including cardiovascular disease, hypertension and stroke, which can complicate disease management. This review examines the aetiology of the linkages between diabetes and obesity and the range of available therapies. Recent clinical evidence substantiating the efficacy and safety of incretin‐based antidiabetic therapies is analysed, in addition to data on antiobesity therapeutic strategies, such as antiobesity agents, behaviour modification and bariatric surgery. Glucose control is often accompanied by weight‐neutral or modest weight reduction effects with DPP‐4 inhibitor treatment (sitagliptin, vildagliptin, saxagliptin) and weight loss with GLP‐1 receptor agonist therapy (exenatide, liraglutide). Studies of antiobesity agents including orlistat, sibutramine and rimonabant have shown attrition rates of 30–40%, and the long‐term effects of these agents remain unknown. Bariatric surgical procedures commonly performed are laparoscopic adjustable banding of the stomach and the Roux‐en‐Y gastric bypass, and have produced type 2 diabetes remission rates of up to 73%. Therapeutic strategies that integrate glycaemic control and weight loss will assume greater importance as the prevalence of diabetes and obesity increase.     

Achieving a clinically relevant composite outcome of an HbA1c of <7% without weight gain or hypoglycaemia in type 2 diabetes: a meta-analysis of the liraglutide clinical trial programme

Aim: Effective type 2 diabetes management requires a multifactorial approach extending beyond glycaemic control. Clinical practice guidelines suggest targets for HbA1c, blood pressure and lipids, and emphasize weight reduction and avoiding hypoglycaemia. The phase 3 clinical trial programme for liraglutide, a human glucagon‐like peptide 1 analogue, showed significant improvements in HbA1c and weight with a low risk of hypoglycaemia compared to other diabetes therapies. In this context, we performed a meta‐analysis of data from these trials evaluating the proportion of patients achieving a clinically relevant composite measure of diabetes control consisting of an HbA1c <7% without weight gain or hypoglycaemia. Methods: A prespecified meta‐analysis was performed on 26‐week patient‐level data from seven trials (N = 4625) evaluating liraglutide with commonly used therapies for type 2 diabetes: glimepiride, rosiglitazone, glargine, exenatide, sitagliptin or placebo, adjusting for baseline HbA1c and weight, for a composite outcome of HbA1c <7.0%, no weight gain and no hypoglycaemic events. Results: At 26 weeks, 40% of the liraglutide 1.8 mg group, 32% of the liraglutide 1.2 mg group and 6–25% of comparators (6% rosiglitazone, 8% glimepiride, 15% glargine, 25% exenatide, 11% sitagliptin, 8% placebo) achieved this composite outcome. Odds ratios favoured liraglutide 1.8 mg by 2.0‐ to 10.5‐fold over comparators. Conclusions: As assessed by the composite outcome of HbA1c <7%, no hypoglycaemia and no weight gain, liraglutide was clearly superior to the other commonly used therapies. However, the long‐term clinical impact of this observation remains to be shown.     

Semaglutide as a therapeutic option for elderly patients with type 2 diabetes: Pooled analysis of the SUSTAIN 1‐5 trials

The efficacy and safety of semaglutide vs comparators in non‐elderly (<65 years) and elderly (≥65 years) patients with type 2 diabetes (T2D) across the SUSTAIN 1‐5 trials were evaluated. Patients were randomized to once‐weekly subcutaneous semaglutide (0.5 or 1.0 mg) vs placebo, sitagliptin, exenatide or insulin. The primary objective was change in HbA1c and secondary objectives were changes in body weight and safety. Mean HbA1c decreased from baseline by 1.2%‐1.5% and 1.5%‐1.9% vs 0%‐0.9% (non‐elderly, n = 3045) and by 1.3%‐1.5% and 1.2%‐1.8% vs 0.2%‐1.0% (elderly, n = 854) with semaglutide 0.5 and 1.0 mg vs comparators. Similar reductions from baseline in mean body weight with semaglutide occurred in both age groups. Similar proportions of patients experienced adverse events; premature treatment discontinuations were higher in elderly vs non‐elderly patients. No increased risk of severe or blood glucose‐confirmed hypoglycaemia was seen with semaglutide vs comparators between age groups. Semaglutide had a comparable efficacy and safety profile in non‐elderly and elderly patients across the SUSTAIN 1‐5 trials, making it an effective treatment option for elderly patients with T2D.     

GLP-1: physiological effects and potential therapeutic applications

Glucagon-like peptide 1 (GLP-1) is a gut-derived incretin hormone with the potential to change diabetes. The physiological effects of GLP-1 are multiple, and many seem to ameliorate the different conditions defining the diverse physiopathology seen in type 2 diabetes. In animal studies, GLP-1 stimulates beta-cell proliferation and neogenesis and inhibits beta-cell apoptosis. In humans, GLP-1 stimulates insulin secretion and inhibits glucagon and gastrointestinal secretions and motility. It enhances satiety and reduces food intake and has beneficial effects on cardiovascular function and endothelial dysfunction. Enhancing incretin action for therapeutic use includes GLP-1 receptor agonists resistant to degradation (incretin mimetics) and dipeptidyl peptidase (DPP)-4 inhibitors. In clinical trials with type 2 diabetic patients on various oral antidiabetic regimes, both treatment modalities efficaciously improve glycaemic control and beta-cell function. Whereas the incretin mimetics induce weight loss, the DPP-4 inhibitors are considered weight neutral. In type 1 diabetes, treatment with GLP-1 shows promising effects. However, several areas need clinical confirmation: the durability of the weight loss, the ability to preserve functional beta-cell mass and the applicability in other than type 2 diabetes. As such, long-term studies and studies with cardiovascular end-points are needed to confirm the true benefits of these new classes of antidiabetic drugs in the treatment of diabetes mellitus.     

Safety, efficacy and tolerability of exenatide in combination with insulin in the Association of British Clinical Diabetologists nationwide exenatide audit*

Aim: To assess the extent, safety, efficacy and tolerability of reported off‐licence exenatide use through a nationwide audit. Methods: The Association of British Clinical Diabetologists hosted a password‐protected, online collection of anonymized data of exenatide use in real clinical practice. Three hundred and fifteen contributors from 126 centres across UK provided data on 6717 patients. HbA1c and weight changes, exenatide discontinuation, adverse events and treatment satisfaction were compared between non‐insulin and insulin‐treated patients. Results: Four thousand eight hundred and fifty‐seven patients had baseline and follow‐up treatment status with mean (±s.d.) baseline HbA1c 9.45 ± 1.69% and BMI 40.0 ± 8.2 kg/m². Of the 4857 patients, 1921 (39.6%) used exenatide with insulin. Comparing patients who continued insulin with exenatide with non‐insulin‐treated patients, mean (±s.e.) latest HbA1c and weight reduction (median 26 weeks) were 0.51 ± 0.06 versus 0.94 ± 0.04% (p < 0.001) and 5.8 ± 0.2 versus 5.5 ± 0.1 kg (p = 0.278). Insulin‐treated patients had higher rates of exenatide discontinuation (31.0 vs. 13.9%, p < 0.001), hypoglycaemia (8.9 vs. 6.1%, p < 0.001), gastrointestinal side effects (28.4 vs. 25.0%, p = 0.008) and treatment dissatisfaction (20.8 vs. 5.7%, p < 0.001). However, 34.2% of the patients continuing insulin still achieved HbA1c reduction ≥1%. There was significant insulin discontinuation, dose reduction and greater sulphonylurea discontinuation among insulin‐treated patients. Conclusions: Addition of exenatide to obese, insulin‐treated patients can improve glycaemia and weight. Adverse events were statistically but probably not clinically significantly higher, but combination treatment was less well tolerated. Overall, exenatide was less effective in lowering HbA1c among insulin‐treated patients, although significant number of insulin‐treated patients still achieved significant HbA1c, weight and insulin reductions. Further research into identifying obese, insulin‐treated patients who will tolerate and benefit from exenatide treatment is urgently needed.     

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.     

The safety and tolerability of GLP-1 receptor agonists in the treatment of type 2 diabetes: a review

Although several classes of pharmacotherapy are available for type 2 diabetes, glycaemic control is often hampered by medication-related adverse effects and contraindications such as renal impairment. Glucagon-like peptide-1 (GLP-1) receptor agonists provide a new pharmacotherapeutic option based on the multiple glucose-lowering effects of the human hormone GLP-1. This mechanism of action not only provides therapeutic efficacy but also suggests that GLP-1 receptor agonists have distinct safety and tolerability concerns compared with other diabetes therapies. Stimulation of pancreatic insulin secretion by GLP-1 receptor agonists is glucose dependent, conferring a lesser risk of hypoglycaemia than that seen with sulfonylureas. Individual GLP-1 receptor agonists differ in their metabolism and excretion profiles, affecting the choice of agent for patients with renal impairment. As with other protein-based therapies, GLP-1 receptor agonists may induce the formation of antibodies that may attenuate therapeutic efficacy and affect safety. Conclusions on cardiovascular safety must await outcomes studies, but at present no signal of harm has been reported, and preclinical data and effects on risk markers suggest a potential for benefit. Current data on thyroid medullary cancer in humans and pancreatic malignancy in rodents do not suggest that there is any reason to restrict the clinical use of GLP-1 analogues in most people with diabetes. It is currently difficult to ascertain the possible contributory role of GLP-1 receptor agonists in increasing the risk of pancreatitis, and vigilance for signs and symptoms is prudent. Primary tolerability issues include transient gastrointestinal symptoms, common with GLP-1 receptor agonists, which can be reduced through dose titration.     

Incretin-based therapies--review of the physiology, pharmacology and emerging clinical experience

Diabetes therapies based on manipulation of the incretin system are now widely available, with millions of people receiving treatment. The incretin hormones, glucose-dependent insulinotropic peptide and glucagon-like peptide-1 are released from endocrine cells in the small intestinal mucosa primarily in response to oral nutrient ingestion. They have various effects, but those most relevant to metabolic dysfunction include stimulation of insulin and suppression of glucagon secretion, with resultant reduction in fasting and postprandial glucose. Incretin secretion and/or action is impaired in type 2 diabetes, leading to development of strategies aimed at redressing this abnormality. These strategies include pharmacological inhibition of dipeptidyl peptidase-4, the enzyme responsible for the short half-life of endogenous incretins, and administration of long-acting dipeptidyl peptidase-4-resistant peptides that bind to and activate the glucagon-like peptide-1 receptor. In this review, we address aspects of incretin biology and pharmacotherapy with a view to highlighting potentially clinically relevant issues and areas of basic research that may impinge on these.     

Glucagon‐like peptide‐1 receptor agonists and risk of acute pancreatitis in patients with type 2 diabetes

Glucagon‐like peptide‐1 receptor agonist (GLP‐1RAs) labels warn about acute pancreatitis (AP) and impose upon doctors the obligation to inform patients about symptoms of AP. Here we systematically reviewed the risk of AP in randomized placebo‐controlled trials (RCTs) investigating the effect of GLP‐1RAs in type 2 diabetes. We performed a systematic review with meta‐analysis of long‐term (minimum 24 months), placebo‐controlled GLP‐1RA RCTs in which AP was a predefined adverse event and adjudicated by blinded and independent adjudicating committees. Three high‐quality RCTs included a total of 9347 GLP‐1RA‐treated and 9353 placebo‐treated patients with type 2 diabetes. Compared to placebo, treatment with GLP1‐RA was not associated with increased risk of AP (Peto odds ratio 0.745 [95% CI, 0.47‐1.17]). Trial Sequential Analysis suggested that additional evidence is needed. In conclusion, this review found no evidence that treatment with GLP‐1RA increases the risk of AP in patients with type 2 diabetes.     

Incretin therapies: highlighting common features and differences in the modes of action of glucagon‐like peptide‐1 receptor agonists and dipeptidyl peptidase‐4 inhibitors

Over the last few years, incretin‐based therapies have emerged as important agents in the treatment of type 2 diabetes (T2D). These agents exert their effect via the incretin system, specifically targeting the receptor for the incretin hormone glucagon‐like peptide 1 (GLP‐1), which is partly responsible for augmenting glucose‐dependent insulin secretion in response to nutrient intake (the ‘incretin effect’). In patients with T2D, pharmacological doses/concentrations of GLP‐1 can compensate for the inability of diabetic β cells to respond to the main incretin hormone glucose‐dependent insulinotropic polypeptide, and this is therefore a suitable parent compound for incretin‐based glucose‐lowering medications. Two classes of incretin‐based therapies are available: GLP‐1 receptor agonists (GLP‐1RAs) and dipeptidyl peptidase‐4 (DPP‐4) inhibitors. GLP‐1RAs promote GLP‐1 receptor (GLP‐1R) signalling by providing GLP‐1R stimulation through ‘incretin mimetics’ circulating at pharmacological concentrations, whereas DPP‐4 inhibitors prevent the degradation of endogenously released GLP‐1. Both agents produce reductions in plasma glucose and, as a result of their glucose‐dependent mode of action, this is associated with low rates of hypoglycaemia; however, there are distinct modes of action resulting in differing efficacy and tolerability profiles. Furthermore, as their actions are not restricted to stimulating insulin secretion, these agents have also been associated with additional non‐glycaemic benefits such as weight loss, improvements in β‐cell function and cardiovascular risk markers. These attributes have made incretin therapies attractive treatments for the management of T2D and have presented physicians with an opportunity to tailor treatment plans. This review endeavours to outline the commonalities and differences among incretin‐based therapies and to provide guidance regarding agents most suitable for treating T2D in individual patients.     

Pharmacological management of type 2 diabetes: the potential of incretin-based therapies

Management guidelines recommend metformin as the first-line therapy for most patients with type 2 diabetes uncontrolled by diet and exercise. Efficacy with metformin therapy is usually of limited duration, which necessitates the early introduction of one or two additional oral agents or the initiation of injections, glucagon-like peptide-1 (GLP-1) agonists or insulin. Although safe and effective, metformin monotherapy has been associated with gastrointestinal side effects (≈20% of treated patients in randomized studies) and is contraindicated in patients with renal insufficiency or severe liver disease. Patients treated with a sulphonylurea are at increased risk for hypoglycaemia and moderate weight gain, whereas those receiving a thiazolidinedione are subject to an increased risk of weight gain, oedema, heart failure or fracture. Weight gain and hypoglycaemia are associated with insulin use. Thus, there is an unmet need for a safe and efficacious add-on agent after initial-therapy failure. Evidence suggests that incretin-based agents, such as GLP-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, can successfully achieve glycaemic targets and potentially provide cardiovascular and β-cell-function benefits. This review will examine current approaches for treating type 2 diabetes and discuss the place of incretin therapies, mainly GLP-1 agonists, in the type 2 diabetes treatment spectrum.     

Targeting Incretins in Type 2 Diabetes: Role of GLP-1 Receptor Agonists and DPP-4 Inhibitors

Until recently, the pathogenesis of type 2 diabetes mellitus (T2DM) has been conceptualized in terms of the predominant defects in insulin secretion and insulin action. It is now recognized that abnormalities in other hormones also contribute to the development of hyperglycemia. For example, the incretin effect, mediated by glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), is attenuated in T2DM. Intravenous administration of GLP-1 ameliorates hyperglycemia in patients with T2DM, but an extremely short half-life limits its utility as a therapeutic agent. Strategies to leverage the beneficial effects of GLP-1 include GLP-1 receptor agonists or analogs or dipeptidyl peptidase-4 (DPP-4) inhibitors-agents that act by slowing the inactivation of endogenous GLP-1 and GIP. The GLP-1 agonist exenatide has been shown to improve HbA1c and decrease body weight. However, exenatide is limited by its relatively short pharmacologic half-life, various gastrointestinal (GI) side effects, and the development of antibodies. Studies of a long-acting exenatide formulation suggest that it has improved efficacy and also promotes weight loss. Another prospect is liraglutide, a once-daily human GLP-1 analog. In phase 2 studies, liraglutide lowered HbA1c by up to 1.7% and weight by approximately 3 kg, with apparently fewer GI side effects than exenatide. DPP-4 inhibitors such as sitagliptin and vildagliptin result in clinically significant reductions in HbA1c, and are weight neutral with few GI side effects. This review will provide an overview of current and emerging agents that augment the incretin system with a focus on the role of GLP-1 receptor agonists and DPP-4 inhibitors.     

Liraglutide provides similar glycaemic control as glimepiride (both in combination with metformin) and reduces body weight and systolic blood pressure in Asian population with type 2 diabetes from China, South Korea and India: a 16-week, randomized, double-blind, active control trial(*)

Aim: To assess and compare the efficacy and safety of liraglutide with those of glimepiride, both in combination with metformin for the treatment of type 2 diabetes in Asian population from China, South Korea and India. Methods: A 16‐week, randomized, double‐blind, double‐dummy, four‐arm, active control trial was carried out. In total, 929 subjects with type 2 diabetes with a mean (±s.d.) age of 53.3 ± 9.5 years, HbA_1c of 8.6 ± 1.0% and body weight of 68.1 ± 11.7 kg were randomized (liraglutide 0.6, 1.2 or 1.8 mg once daily or glimepiride 4 mg once daily all in combination with metformin: 1 : 1 : 1 : 1). One subject withdrew immediately after randomization and before exposure. Results: HbA_1c was significantly reduced in all groups compared with baseline. Treatment with liraglutide 1.2 and 1.8 mg was non‐inferior to glimepiride (mean HbA_1c reduction: 1.36% points, 1.45% points and 1.39% points, respectively). No significant difference was shown in the percentage of subjects reaching American Diabetes Association HbA_1c target <7% or American Association of Clinical Endocrinologists target ≤6.5% between liraglutide 1.2 and 1.8 mg and glimepiride. Liraglutide was associated with a 1.8–2.4 kg mean weight reduction, compared with a 0.1 kg mean weight gain with glimepiride. Liraglutide led to a significantly greater reduction in systolic blood pressure (SBP) compared with glimepiride. Two subjects in the glimepiride group reported major hypoglycaemia while none in the liraglutide groups. Liraglutide was associated with about 10‐fold lower incidence of minor hypoglycaemia than glimepiride. Gastrointestinal disorders were the most common adverse events (AEs) for liraglutide, but were transient and resulted in few withdrawals. Conclusions: In Asian subjects with type 2 diabetes, once‐daily liraglutide led to improvement in glycaemic control similar to that with glimepiride but with less frequent major and minor hypoglycaemia. Liraglutide also induced a significant weight loss and reduced SBP and was generally well tolerated. The most frequently reported AE was transient nausea. The effect of liraglutide in this Asian population is comparable to the effects seen in Caucasian, African American and Hispanic populations in global liraglutide phase 3 trials.