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 β-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) β-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 β-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.     

Combination treatment with alogliptin and voglibose increases active GLP‐1 circulation,prevents the development of diabetes and preserves pancreatic beta‐cells in prediabetic db/db mice

Aim: Alogliptin, a dipeptidyl peptidase‐4 (DPP‐4) inhibitor, and voglibose, an alpha‐glucosidase inhibitor, have different but complementary mechanisms of action on glucagon‐like peptide‐1 (GLP‐1) regulation and glucose‐lowering effects. The present study evaluated the chronic effects of combination treatment with alogliptin and voglibose in prediabetic db/db mice. Methods: Alogliptin (0.03%) and voglibose (0.001%) alone or in combination were administered in the diet to prediabetic db/db mice. Results: After 3 weeks, voglibose treatment increased GLP‐1 secretion (voglibose alone, 1.6‐fold; alogliptin plus voglibose, 1.5‐fold), while it decreased plasma glucose‐dependent insulinotropic polypeptide (GIP) (voglibose alone, ?30%; alogliptin plus voglibose, ?29%). Alogliptin, voglibose and combination treatment decreased plasma DPP‐4 activity by 72, 15 and additively by 80%, respectively, and increased plasma active GLP‐1 levels by 4.5‐, 1.8‐ and synergistically by 9.1‐fold respectively. Combination treatment increased plasma insulin by 3.6‐fold (alogliptin alone, 1.3‐fold; voglibose alone, 1.8‐fold), decreased plasma glucagon by 30% (alogliptin alone, 11%; voglibose alone, 8%), and prevented the development of diabetes, much more effectively than either agent alone. After 4 weeks, alogliptin, voglibose and combination treatment increased pancreatic insulin content by 1.6‐, 3.4‐ and synergistically by 8.5‐fold respectively. Furthermore, combination treatment resulted in an increased expression of insulin, pancreatic and duodenal homeobox 1 (PDX1) and glucose transporter 2 (GLUT2), and maintenance of normal beta/alpha‐cell distribution in the pancreatic islet. Conclusions: Chronic treatment with alogliptin in combination with voglibose concurrently increased active GLP‐1 circulation, increased insulin secretion, decreased glucagon secretion, prevented the onset of the disease, and preserved pancreatic beta‐cells and islet structure in prediabetic db/db mice.     

Type 2 diabetes mellitus and heart failure: a position statement from the Heart Failure Association of the European Society of Cardiology

The coexistence of type 2 diabetes mellitus (T2DM) and heart failure (HF), either with reduced (HFrEF) or preserved ejection fraction (HFpEF), is frequent (30–40% of patients) and associated with a higher risk of HF hospitalization, all‐cause and cardiovascular (CV) mortality. The most important causes of HF in T2DM are coronary artery disease, arterial hypertension and a direct detrimental effect of T2DM on the myocardium. T2DM is often unrecognized in HF patients, and vice versa, which emphasizes the importance of an active search for both disorders in the clinical practice. There are no specific limitations to HF treatment in T2DM. Subanalyses of trials addressing HF treatment in the general population have shown that all HF therapies are similarly effective regardless of T2DM. Concerning T2DM treatment in HF patients, most guidelines currently recommend metformin as the first‐line choice. Sulphonylureas and insulin have been the traditional second‐ and third‐line therapies although their safety in HF is equivocal. Neither glucagon‐like preptide‐1 (GLP‐1) receptor agonists, nor dipeptidyl peptidase‐4 (DPP4) inhibitors reduce the risk for HF hospitalization. Indeed, a DPP4 inhibitor, saxagliptin, has been associated with a higher risk of HF hospitalization. Thiazolidinediones (pioglitazone and rosiglitazone) are contraindicated in patients with (or at risk of) HF. In recent trials, sodium–glucose co‐transporter‐2 (SGLT2) inhibitors, empagliflozin and canagliflozin, have both shown a significant reduction in HF hospitalization in patients with established CV disease or at risk of CV disease. Several ongoing trials should provide an insight into the effectiveness of SGLT2 inhibitors in patients with HFrEF and HFpEF in the absence of T2DM.     

Meta‐analysis on the efficacy and safety of SGLT2 inhibitors and incretin based agents combination therapy vs. SGLT2i alone or add‐on to metformin in type 2 diabetes

We aimed to determine whether sodium‐glucose cotransporter type 2 inhibitors (SGLT2is) and incretin‐based agents combination therapy produces more benefits than SGLT2is alone in patients with type 2 diabetes mellitus (T2DM). PubMed, Embase, and the Cochrane Library were searched for randomized controlled trials (RCTs) comparing SGLT2is plus Dipeptidyl‐Peptidase 4 inhibitors (SGLT2is/DPP4is) or glucagon like peptide‐1 receptor agonists (SGLT2is/GLP‐1RAs) against SGLT2is as monotherapy or add‐on to metformin in T2DMs. A total of 13 studies with 7350 participants were included. Combination with GLP‐1RAs exhibited more HbA1c reduction (WMD: ?0.8; 95% CI, ?1.14 to ?0.45%), weight loss (?1.46; 95% CI, ?2.38 to ?0.54 kg), and systolic blood pressure (SBP) reduction (?2.88; 95% CI, ?4.52 to ?1.25 mmHg) versus SGLT2is alone but increased the gastrointestinal disorder risk (RR: 1.68; 95% CI, 1.14‐2.47). Combination with DPP4is exhibited an extra effect on HbA1c reduction (?0.47; 95% CI, ?0.58 to ?0.37%), a neutral effect on weight (0.19; 95% CI, ?0.11 to 0.48 kg) and SBP (?0.01; 95% CI, ?0.85 to 0.63 mmHg), and ameliorated the genital infections risk (0.73; 95% CI, 0.54‐0.97) versus SGLT2is. Meta‐regression indicated the hypoglycemic efficacy of SGLT2is/DPP4is is higher in Asians than in other ethnics, and the differences in BMI across ethnic groups may mediate this effect. SGLT2is and incretin‐based agents combination therapy is efficacious and safe versus SGLT2is alone in T2DMs. Particularly, combination with GLP‐1RAs shows additional benefits to glycemic, weight, and SBP control to a larger extent than DPP4is, while combination with DPP4is ameliorates the risk for genital infection seen with SGLT2is. We highlight the need for individualized treatment related to the selection of this novel combination therapy.     

European Society of Cardiology/Heart Failure Association position paper on the role and safety of new glucose‐lowering drugs in patients with heart failure

Type 2 diabetes mellitus (T2DM) is common in patients with heart failure (HF) and associated with considerable morbidity and mortality. Significant advances have recently occurred in the treatment of T2DM, with evidence of several new glucose‐lowering medications showing either neutral or beneficial cardiovascular effects. However, some of these agents have safety characteristics with strong practical implications in HF [i.e. dipeptidyl peptidase‐4 (DPP‐4) inhibitors, glucagon‐like peptide‐1 receptor agonists (GLP‐1 RA), and sodium–glucose co‐transporter type 2 (SGLT‐2) inhibitors]. Regarding safety of DPP‐4 inhibitors, saxagliptin is not recommended in HF because of a greater risk of HF hospitalisation. There is no compelling evidence of excess HF risk with the other DPP‐4 inhibitors. GLP‐1 RAs have an overall neutral effect on HF outcomes. However, a signal of harm suggested in two small trials of liraglutide in patients with reduced ejection fraction indicates that their role remains to be defined in established HF. SGLT‐2 inhibitors (empagliflozin, canagliflozin and dapagliflozin) have shown a consistent reduction in the risk of HF hospitalisation regardless of baseline cardiovascular risk or history of HF. Accordingly, SGLT‐2 inhibitors could be recommended to prevent HF hospitalisation in patients with T2DM and established cardiovascular disease or with multiple risk factors. The recently completed trial with dapagliflozin has shown a significant reduction in cardiovascular mortality and HF events in patients with HF and reduced ejection fraction, with or without T2DM. Several ongoing trials will assess whether the results observed with dapagliflozin could be extended to other SGLT‐2 inhibitors in the treatment of HF, with either preserved or reduced ejection fraction, regardless of the presence of T2DM. This position paper aims to summarise relevant clinical trial evidence concerning the role and safety of new glucose‐lowering therapies in patients with HF.     

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.     

Heart failure outcomes in clinical trials of glucose‐lowering agents in patients with diabetes

Diabetes is a major risk factor for heart failure (HF). Patients with diabetes have a high incidence of both clinical HF and subclinical LV dysfunction. Although intensive glucose lowering does not appear to impact on HF outcomes, the choice of glucose‐lowering agents plays an important role in the development of HF and related cardiovascular outcomes. Whilst metformin and insulin appear to have little impact on HF progression, the role of sulphonylurea agents in this patient population remains uncertain. Thiazolidinediones (TZDs) are associated with a significant risk of HF progression and are best avoided in patients at risk. The incretin‐based therapies (GLP agonists and DPP‐4 inhibitors) are generally not associated with any HF interaction. However, a small increase in HF admissions was observed with the DPP‐4 inhibitor saxagliptin. The GLP‐1 agonist liraglutide was recently shown to reduce cardiovascular and all‐cause mortality, yet hospitalization for HF was not significantly reduced. The SGLT2 inhibitor empagliflozin was shown to reduce HF admissions and cardiovascular mortality in patients with prior cardiovascular disease including HF. These recent data showing improved outcomes with a glucose‐lowering category provide a novel strategy to improve survival and reduce morbidity in diabetic patients at high cardiovascular disease risk.     

Lixisenatide,a novel GLP‐1 receptor agonist: efficacy,safety and clinical implications for type 2 diabetes mellitus

Recent advances in therapies for the treatment of type 2 diabetes mellitus (T2DM) have led to the development of glucagon‐like peptide‐1 receptor agonists (GLP‐1 RAs), which, unlike insulin and sulphonylurea, are effective, with a low risk of hypoglycaemia. Lixisenatide is recommended as a once‐daily GLP‐1 RA for the treatment of T2DM. In persons with T2DM, lixisenatide 20 µg once‐daily given by bolus subcutaneous injection improves insulin secretion and suppresses glucagon secretion in a glucose‐dependent manner. Compared with the longer‐acting GLP‐1 RA liraglutide, lixisenatide achieved a significantly greater reduction in postprandial plasma glucose (PPG) during a standardized test breakfast in persons with T2DM otherwise insufficiently controlled on metformin alone. This is primarily due to the greater inhibition of gastric motility by lixisenatide compared with liraglutide. The efficacy and safety of lixisenatide was evaluated across a spectrum of T2DM in a series of phase III, randomized, placebo‐controlled trials known as the GetGoal programme. Lixisenatide monotherapy or as add‐on to oral antidiabetic agents or basal insulin achieved significant reductions in glycated haemoglobin, PPG and fasting plasma glucose, with either weight loss or no weight gain. The most frequent adverse events were gastrointestinal and transient in nature. Lixisenatide provides an easy, once‐daily, single‐dose, add‐on treatment to oral antidiabetic agents or basal insulin for the management of T2DM, with little or no increased risk of hypoglycaemia and a potential beneficial effect on body weight.     

Glucose‐dependent insulinotropic polypeptide and glucagon‐like peptide‐1: Incretin actions beyond the pancreas

Glucose‐dependent insulinotropic polypeptide (GIP) and glucagon‐like peptide‐1 (GLP‐1) are the two primary incretin hormones secreted from the intestine on ingestion of various nutrients to stimulate insulin secretion from pancreatic β‐cells glucose‐dependently. GIP and GLP‐1 undergo degradation by dipeptidyl peptidase‐4 (DPP‐4), and rapidly lose their biological activities. The actions of GIP and GLP‐1 are mediated by their specific receptors, the GIP receptor (GIPR) and the GLP‐1 receptor (GLP‐1R), which are expressed in pancreatic β‐cells, as well as in various tissues and organs. A series of investigations using mice lacking GIPR and/or GLP‐1R, as well as mice lacking DPP‐4, showed involvement of GIP and GLP‐1 in divergent biological activities, some of which could have implications for preventing diabetes‐related microvascular complications (e.g., retinopathy, nephropathy and neuropathy) and macrovascular complications (e.g., coronary artery disease, peripheral artery disease and cerebrovascular disease), as well as diabetes‐related comorbidity (e.g., obesity, non‐alcoholic fatty liver disease, bone fracture and cognitive dysfunction). Furthermore, recent studies using incretin‐based drugs, such as GLP‐1 receptor agonists, which stably activate GLP‐1R signaling, and DPP‐4 inhibitors, which enhance both GLP‐1R and GIPR signaling, showed that GLP‐1 and GIP exert effects possibly linked to prevention or treatment of diabetes‐related complications and comorbidities independently of hyperglycemia. We review recent findings on the extrapancreatic effects of GIP and GLP‐1 on the heart, brain, kidney, eye and nerves, as well as in the liver, fat and several organs from the perspective of diabetes‐related complications and comorbidities.     

Change in glycated haemoglobin levels after initiating second‐line therapy in type 2 diabetes: a primary care database study

The aim of the present study was to compare the absolute reduction in glycated haemoglobin (HbA1c) levels at 6 months after initiating second‐line glucose‐lowering therapy in patients with type 2 diabetes treated with metformin monotherapy in general practices. A total of 7009 patients were identified (Disease Analyser Germany: January 2004 to December 2014). The patients' mean ± standard deviation (s.d.) age was 63 ± 11 years, 55.5% were male and their mean ± s.d. HbA1c level was 8.0 ± 1.6%. The initiated second‐line therapies included: dipeptidyl peptidase‐4 (DPP‐4) inhibitors (38.7%); sulphonylureas (36.3%); insulin (13.3%); glucagon‐like peptide‐1 receptor agonists (GLP‐1RAs; 2.5%); thiazolidinediones (5%); and other agents (glinides, aldose‐reductase inhibitors; 4.1%). The mean absolute HbA1c change from baseline was ?0.9% (DPP‐4 inhibitors, ?0.9%; sulphonylureas, ?0.9%; insulin, ?1.1%; GLP‐1RAs, ?0.7%; thiazolidinediones, ?0.9%; and other, ?0.7%; all p < 0.001). Overall, 58% of patients reached the HbA1c target of <7% (DPP‐4 inhibitors, 61.7%; sulphonylureas, 56.7%; insulin, 45.6%; GLP‐1RAs, 62.2%; thiazolidinediones, 69.7%; and other, 57.5%). Compared with sulphonlyureas, DPP‐4 inhibitors, GLP‐1RAs and thiazolidinediones were associated with an increased odds of reaching HbA1c <7% [odds ratio (OR) 1.24, 95% confidence interval (CI) 1.09–1.40; OR 1.43, 95% CI 1.01–2.04; and OR 1.70, 95% CI 1.30–2.23, respectively], whereas insulin was related to a lower odds (0.66, 95% CI 0.55–0.78). In conclusion, in patients with type 2 diabetes very similar reductions in HbA1c after 6 months of second‐line therapy were achieved regardless of the type of therapy.     

Pharmacokinetics of dipeptidylpeptidase‐4 inhibitors

Type 2 diabetes (T2DM) is a complex disease combining defects in insulin secretion and insulin action. New compounds have been developed for improving glucose‐induced insulin secretion and glucose control, without inducing hypoglycaemia or weight gain. Dipeptidylpeptidase‐4 (DPP‐4) inhibitors are new oral glucose‐lowering agents, so‐called incretin enhancers, which may be used as monotherapy or in combination with other antidiabetic compounds. Sitagliptin, vildaglipin and saxagliptin are already on the market in many countries, either as single agents or in fixed‐dose combined formulations with metformin. Other DPP‐4 inhibitors, such as alogliptin and linagliptin, are currently in late phase of development. The present paper summarizes and compares the main pharmacokinetics (PK) properties, that is, absorption, distribution, metabolism and elimination, of these five DPP‐4 inhibitors. Available data were obtained in clinical trials performed in healthy young male subjects, patients with T2DM, and patients with either renal insufficiency or hepatic impairment. PK characteristics were generally similar in young healthy subjects and in middle‐aged overweight patients with diabetes. All together gliptins have a good oral bioavailability which is not significantly influenced by food intake. PK/pharmacodynamics characteristics, that is, sufficiently prolonged half‐life and sustained DPP‐4 enzyme inactivation, generally allow one single oral administration per day for the management of T2DM; the only exception is vildagliptin for which a twice‐daily administration is recommended because of a shorter half‐life. DPP‐4 inhibitors are in general not substrates for cytochrome P450 (except saxagliptin that is metabolized via CYP 3A4/A5) and do not act as inducers or inhibitors of this system. Several metabolites have been documented but most of them are inactive; however, the main metabolite of saxagliptin also exerts a significant DPP‐4 inhibition and is half as potent as the parent compound. Renal excretion is the most important elimination pathway, except for linagliptin whose metabolism in the liver appears to be predominant. PK properties of gliptins, combined with their good safety profile, explain why no dose adjustment is necessary in elderly patients or in patients with mild to moderate hepatic impairment. As far as patients with renal impairment are concerned, significant increases in drug exposure for sitagliptin and saxagliptin have been reported so that appropriate reductions in daily dosages are recommended according to estimated glomerular filtration rate. The PK characteristics of DPP‐4 inhibitors suggest that these compounds are not exposed to a high risk of drug–drug interactions. However, the daily dose of saxagliptin should be reduced when coadministered with potent CYP 3A4 inhibitors. In conclusion, besides their pharmacodynamic properties leading to effective glucose‐lowering effect without inducing hypoglycaemia or weight gain, DPP‐4 inhibitors show favourable PK properties, which contribute to a good efficacy/safety ratio for the management of T2DM in clinical practice.     

Effects of neprilysin and neprilysin inhibitors on glucose homeostasis: Controversial points and a promising arena

Neprilysin (NEP) is a transmembrane zinc-dependent metalloproteinase that inactivates various peptide hormones including glucagon-like peptide 1 (GLP-1). NEP inhibitors may be effective in the management of type 2 diabetes mellitus (T2DM) by increasing the circulating level of GLP-1. However, acute-effect NEP inhibitors may lead to detrimental effects by increasing blood glucose independent of GLP-1. These findings suggest a controversial point regarding the potential role of NEP inhibitors on glucose homeostasis in T2DM patients. Therefore, this perspective aimed to clarify the controversial points concerning the role of NEP inhibitors on glucose homeostasis in T2DM. NEP inhibitors may lead to beneficial effects by inhibition of NEP, which is involved in the impairment of glucose homeostasis through modulation of insulin resistance. NEP increases dipeptidyl peptidase-4 (DPP4) activity and contributes to increasing active GLP-1 proteolysis so NEP inhibitors may improve glycemic control through increasing endogenous GLP-1 activity and reduction of DPP4 activity. Thus, NEP inhibitors could be effective alone or in combination with antidiabetic agents in treating T2DM patients. However, long-term and short-term effects of NEP inhibitors may lead to a detrimental effect on insulin sensitivity and glucose homeostasis through different mechanisms including augmentation of substrates and pancreatic amyloid deposition. These findings are confirmed in animal but not in humans. In conclusion, NEP inhibitors produce beneficial rather than detrimental effects on glucose homeostasis and insulin sensitivity in humans though most of the detrimental effects of NEP inhibitors are confirmed in animal studies.     

Incretin-based therapy and pancreatic beta cells

Type 2 diabetes (T2D) is a complex, progressive disease with life-threatening complications and one of the most serious public-health problems worldwide. The two main mechanisms of T2D pathogenesis are pancreatic beta cell dysfunction and insulin resistance. It is now recognized that pancreatic beta cell dysfunction is a necessary factor for T2D development. Traditional therapies for controlling blood glucose are suboptimal as they fail to meet target goals for many patients. Glucagon-like peptide-1 receptor agonists (GLP1RA) and dipeptidyl peptidase-4 inhibitors (DPP4I) are an attractive class of therapy because they reduce blood glucose by targeting the incretin hormone system and, in particular, have the potential to positively affect pancreatic beta cell biology. This review outlines our current understanding of pancreatic beta cell incretin system dysfunction in T2D and summarizes recent evidence of the effect of incretin-based therapies on beta cell function and mass. Incretin-based therapies have shown strong evidence for beneficial effects on beta cell function and mass in animal studies. In humans, incretin-based therapies are effective glucose-lowering agents, but further study is still required to evaluate their long-term effects on beta cell function and safety as well as beta cell mass expansion.     

DPP‐4 inhibition and islet function

During recent years, dipeptidyl peptidase‐4 (DPP‐4) inhibition has been included in the clinical management of type 2 diabetes, both as monotherapy and as add‐on to several other therapies. DPP‐4 inhibition prevents the inactivation of the incretin hormones, glucose‐dependent insulinotropic polypeptide (GIP) and glucagon‐like peptide‐1 (GLP‐1). This results in stimulation of insulin secretion and inhibition of glucagon secretion, and there is also a potential β‐cell preservation effect, as judged from rodent studies; that is, it might target the key islet dysfunction in the disease. In type 2 diabetes. This reduces 24‐h glucose levels and reduces HbA_1c by ≈ 0.8–1.1% from baseline levels of 7.7–8.5%. DPP‐4 inhibition is safe, with a very low risk for adverse events including hypoglycemia, and it prevents weight gain. The present review summarizes the studies on the influence of DPP‐4 inhibition on islet function. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00184.x, 2012)     

Effect of antidiabetic agents added to metformin on glycaemic control, hypoglycaemia and weight change in patients with type 2 diabetes: a network meta-analysis

Aim: Most guidelines recommend metformin as first‐line therapy in patients with type 2 diabetes. However, the choice of a second‐line drug lacks consistent consensus. We aimed to assess available information of antidiabetic drugs added to metformin on the change in glycated haemoglobin A1c (A1C), risk of hypoglycaemia and change in body weight. Methods: PubMed and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials (RCTs) written in English through December 2011. We analysed direct and indirect comparisons of different treatments using Bayesian network meta‐analysis. Results: Thirty‐nine RCTs involving 17 860 individuals were included. Glucagon‐like peptide‐1 (GLP‐1) analogues resulted in greater decrease in A1C compared with sulfonylureas, glinides, thiazolidinediones, α‐glucosidase inhibitors and DPP‐4 inhibitors [?0.20% (95% CI ?0.34 to ?0.04%), ?0.31% (95% CI ?0.61 to ?0.02%), ?0.20% (95% CI ?0.38 to ?0.00), ?0.36% (95% CI ?0.64 to ?0.07%), ?0.32% (95% CI ?0.47 to ?0.17%), respectively] and was comparable with basal insulin and biphasic insulin. A1C decrease was greater for sulfonylureas compared with DPP‐4 inhibitors [?0.12% (?0.23 to ?0.03%)], and for biphasic insulin compared with glinides (?0.36%; 95% CI ?0.82 to ?0.11%). Compared with placebo, the risk of hypoglycaemia was increased in the sulfonylureas, glinides, basal insulin and biphasic insulin. Weight increase was seen with sulfonylureas, glinides, thiazolidinediones, basal insulin and biphasic insulin, and weight loss was seen with α‐glucosidase inhibitors and GLP‐1 analogues. Conclusions: Biphasic insulin, GLP‐1 analogues and basal insulin were ranked the top three drugs in terms of A1C reduction. GLP‐1 analogues did not increase the risk of hypoglycaemia and resulted in a significant decrease in body weight. Most oral antidiabetic drugs had similar effects on A1C, but some agents had a lower risk of hypoglycaemia and body weight gain.     

New therapies for type 2 diabetes: what place for incretin-based agents and rimonabant compared to the previous ones?

Treatment of type 2 diabetes (T2DM) is based on lifestyle changes and oral antidiabetic agents or insulin. The UKPDS study has confirmed metformin (Met) as the initial monotherapy. Accordingly, Met is widely regarded as the first drug of choice for most patients with T2DM. Safety and efficacy of sulphonylureas (SU) have been confirmed by several clinical trials. Recently, thiazolidinediones (TZD) have addressed some aspects of insulin-resistance that characterized several T2DM patients. However, SU and TZD are associated with various side effects that limit their use in many patients. New agents have been recently developed which potentiate the activity of the incretin (GLP1). GLP1, a gut hormone secreted in response to meal ingestion, is rapidly degraded by dipeptidylpeptidase-4 (DPP-4). GLP1 enhances insulin secretion and inhibits glucagon secretion in a glucose-dependent manner, delays gastric emptying and, in animal studies, preserves beta-cell mass by reducing apoptosis and stimulates of beta-cell proliferation. GLP1 levels are abnormally low in T2DM patients. Two classes of agents based on GLP1 have been launched: DPP-4 inhibitors and DPP-4 resistant GLP1 analogues. Randomized studies confirmed their efficacy to improve glycemic control in T2DM patients. Orally administered DPP-4 inhibitors reduce HbA1c by 0.5-1.1%, without hypoglycaemic events and no weight gain. The sub-cutaneous injected GLP1 analogues (exenatide and liraglutide) show larger reductions in HbA1c by 0.8-1.7% and weight loss but are associated with gastrointestinal side effects contributing to a significant treatment interruption. Several studies support the use of DPP-4 inhibitors in combination with Met as a promising second line treatment.     

Twelve weeks treatment with the DPP‐4 inhibitor,sitagliptin, prevents degradation of peptide YY and improves glucose and non‐glucose induced insulin secretion in patients with type 2 diabetes mellitus

Aim: To examine the effects of 12 weeks of treatment with the DPP‐4 inhibitor, sitagliptin, on gastrointestinal hormone responses to a standardized mixed meal and beta cell secretory capacity, measured as glucose and non‐glucose induced insulin secretion during a hyperglycaemic clamp, in patients with type 2 diabetes. Method: A double‐blinded, placebo‐controlled study over 12 weeks in which 24 patients with T2DM were randomized to receive either sitagliptin (Januvia) 100 mg qd or placebo as an add‐on therapy to metformin. In week 0, 1 and 12 patients underwent a meal test and a 90‐min 20 mM hyperglycaemic clamp with 5 g of l ‐arginine infusion. Main outcome measure was postprandial total glucagon‐like peptide 1 (GLP‐1) concentration. Additional measures were insulin and C‐peptide, glycaemic control, intact and total peptide YY (PYY) and glucose‐dependent insulinotropic polypeptide (GIP), and intact glucagon‐like peptide 2 (GLP‐2) and GLP‐1. Results: All patients [sitagliptin n = 12, age: 59.5 (39–64) years, HbA1c: 8.0 (7.3–10.0)%, BMI: 33.2 (29.3–39.4); placebo n = 12, age: 60 (31–72) years, HbA1c: 7.7 (7.1–9.8)%, BMI: 30.7 (25.7–40.5)] [median (range)] completed the trial. Sitagliptin treatment improved glycaemic control, had no effect on total GLP‐1, GIP or intact GLP‐2, but reduced total PYY and PYY_{3‐ 36}, and increased PYY_{1‐ 36} and intact incretin hormones. Sitagliptin improved first and second phases of beta cell secretion and maximal secretory capacity. All effects were achieved after 1 week. No significant changes occurred in the placebo group. Conclusion: The postprandial responses of total GLP‐1 and GIP and intact GLP‐2 were unaltered. PYY degradation was prevented. Glucose and non‐glucose induced beta cell secretion was improved. There was no difference in responses to sitagliptin between 1 and 12 weeks of treatment.     

二甲双胍联合二肽基肽酶4抑制剂治疗未达标的2型糖尿病患者应用格列喹酮的疗效研究

目的 比较格列喹酮、预混胰岛素对二甲双胍联合二肽基肽酶4抑制剂(DPP4I)血糖控制不佳的患者降糖效果.方法 选取2017年10月至2019年9月于天津市第四中心医院就诊的应用二甲双胍和DPP4I控制血糖不佳的2型糖尿病患者280例为研究对象,分为格列喹酮和预混胰岛素组,比较两组血糖、体重变化及低血糖情况.结果 格列喹...