Incretin therapies: effects beyond glycemic control

Vildagliptin Attenuates Huntington's Disease through Activation of GLP-1 Receptor/PI3K/Akt/BDNF Pathway in 3-Nitropropionic Acid Rat Model

Vildagliptin (Vilda), a dipeptidyl peptidase-4 (DPP-4) inhibitor, has been highlighted as a promising therapeutic agent for neurodegenerative diseases as Alzheimer's and Parkinson's diseases. Vilda's effect is mostly linked to PI3K/Akt signaling in CNS. Moreover, PI3K/Akt activation reportedly enhanced survival and dampened progression of Huntington's disease (HD). However, Vilda's role in HD is yet to be elucidated. Thus, the aim of the study is to uncover the potentiality of Vilda in HD and unfold its link with PI3K/Akt pathway in 3-nitropropionic acid (3NP) rat model. Rats were randomly assigned into 4 groups; group 1 received saline, whereas, groups 2, 3 and 4 received 3NP (10 mg/kg/day; i.p.) for 14 days, concomitantly with Vilda (5 mg/kg/day; p.o.) in groups 3 and 4, and wortmannin (WM), a PI3K inhibitor, (15 μg/kg/day; i.v.) in group 4. Vilda improved cognitive and motor perturbations induced by 3NP, as confirmed by striatal histopathological specimens and immunohistochemical examination of GFAP. The molecular signaling of Vilda was estimated by elevation of GLP-1 level and protein expressions of survival proteins; p85/p55 (pY458/199)-PI3K, pS473-Akt. Together, it boosted striatal neurotrophic factors and receptor; pS133-CREB, BDNF, pY515-TrKB, which subsequently maintained mitochondrial integrity, as indicated by enhancing both SDH and COX activities, and the redox modulators; Sirt1, Nrf2. Such neuroprotection restored imbalance of neurotransmitters through increasing GABA and suppressing glutamate as well PDE10A. These effects were reversed by WM pre-administration. In conclusion, Vilda purveyed significant anti-Huntington effect which may be mediated, at least in part, via activation of GLP-1/PI3K/Akt pathway in 3NP rat model.

Efficacy and safety of once-weekly dulaglutide in combination with sulphonylurea and/or biguanide compared with once-daily insulin glargine in Japanese patients with type 2 diabetes: a randomized, open-label, phase III, non-inferiority study

AIMS

To evaluate 0.75 mg of dulaglutide, a once-weekly glucagon-like peptide-1 receptor agonist, compared with once-daily insulin glargine for glycaemic control in Japanese patients with type 2 diabetes (T2D).

METHODS

In this phase III, randomized, open-label, parallel-group, 26-week study, 361 patients with inadequately controlled T2D receiving sulphonylureas and/or biguanides, aged ≥20 years, with glycated haemoglobin (HbA1c) levels 7.0-10.0% (53-86 mmol/mol), inclusive, were randomized (1 : 1) to receive dulaglutide or glargine. Participants and investigators were not masked to treatment allocation. The primary measure was change from baseline in HbA1c at 26 weeks, analysed using a mixed-effects model for repeated measures, with a predefined non-inferiority margin of 0.4%.

RESULTS

At week 26, least-squares (LS) mean (standard error) reductions in HbA1c were -1.44 (0.05)% [-15.74 (0.55) mmol/mol] in the dulaglutide group and -0.90 (0.05)% [-9.84 (0.55) mmol/mol] in the glargine group. The mean between-group treatment difference in HbA1c was -0.54% (95% CI -0.67, -0.41) [-5.90 mmol/mol (95% CI -7.32, -4.48)]; p < 0.001. Dulaglutide significantly reduced body weight compared with glargine at week 26 (LS mean difference -1.42 kg, 95% CI -1.89, -0.94; p < 0.001). The most frequent adverse events with dulaglutide treatment were nasopharyngitis and gastrointestinal symptoms. The incidence of hypoglycaemia was significantly lower with dulaglutide [47/181 (26%)] compared with glargine [86/180 (48%)], p < 0.001.

CONCLUSION

In Japanese patients with T2D uncontrolled on sulphonylureas and/or biguanides, once-weekly dulaglutide was superior to once-daily glargine for reduction in HbA1c at 26 weeks. Although dulaglutide increased gastrointestinal symptoms, it was well tolerated, with an acceptable safety profile.

A 1-year safety study of dulaglutide in Japanese patients with type 2 diabetes on a single oral hypoglycemic agent: an open-label, nonrandomized, phase 3 trial

The goal of this study was to assess the safety and efficacy of 0.75 mg of dulaglutide, a once weekly glucagon-like peptide-1 receptor agonist, in Japanese patients with type 2 diabetes (T2D) on a single oral hypoglycemic agent (OHA). In this phase 3, nonrandomized, open-label, parallel-group, 52-week study, safety and efficacy of once weekly dulaglutide 0.75 mg were assessed in Japanese patients with T2D on a single OHA (sulfonylureas [SU], biguanides [BG], α-glucosidase inhibitors [AGI], thiazolidinedione [TZD], or glinides [GLN]). A total of 394 patients were treated with study drug, and 92.9% completed the 52-week treatment period. The most frequent treatment-emergent adverse events were nasopharyngitis and gastrointestinal disorders, including constipation, diarrhea, and nausea. Incidences of hypoglycemia varied across the combination therapy groups: incidence was greater in patients receiving SU compared with other combinations. No severe hypoglycemic episodes occurred during the study. Increases from baseline in pancreatic and total amylase, lipase, and pulse rate were observed in all 5 combination therapy groups. Significant reductions from baseline in HbA1c were observed in all 5 combination therapy groups (-1.57% to -1.69%, p < 0.001 for all). Mean body weight changes from baseline varied across the combination therapy groups: a significant increase was observed in combination with TZD, there were no significant changes in combination with SU or GLN, and significant reductions were observed in combination with BG or AGI. Once weekly dulaglutide 0.75 mg in combination with a single OHA was overall well tolerated and improved glycemic control in Japanese patients with T2D.

Real-world effectiveness of sitagliptin as add-on therapy in patients with type 2 diabetes mellitus

AIMS

To assess the effectiveness of sitagliptin in glycemic control in a clinical practice.

METHODS

This was a retrospective medical chart review study conducted in a single hospital. A total of 3081 patients with diabetes mellitus who were prescribed sitagliptin were selected, including 2729 continuous sitagliptin users (defined as continuous usage ≥ 24 weeks) and 352 subjects who used sitagliptin for < 24 weeks. An additional 12-month observation period was monitored after initiating sitagliptin to extract clinical information at 3, 6, 9, and 12 months through patient medical chart review.

RESULTS

In the 2729 continuous users, a baseline glycated hemoglobin (HbA1c) level of 9.0% was reduced to 8.1%, 8.1%, 8.1%, and 8.2% at 3, 6, 9, and 12 months, respectively, representing a 0.9% HbA1c level reduction at 3, 6, and 9 months and a 0.8% HbA1c level reduction at 12 months. With a goal of HbA1c value of < 7.0%, 9.1% of the patients were under control at baseline; after initiating sitagliptin, 22.7% of the patients achieved the HbA1c level goal at 3 months, 23.6% at 6 months, 20.8% at 9 months, and 20.4% at 12 months. The proportion of patients attaining the goal of HbA1c level < 7.0% at least doubled at different time points after treatment with sitagliptin.

CONCLUSIONS

In this single-hospital retrospective chart analysis, a meaningful clinical improvement in glycemic control before and after sitagliptin treatment commenced, including HbA1c level reduction and the HbA1c goal attainment rate, was observed. The results reflect the actual clinical practice in a large hospital in Taiwan, and supplement data from randomized controlled trials.

Diabetes and cardiovascular disease: focus on glucagon-like peptide-1 based therapies

Type 2 diabetes is a well known risk factor for cardiovascular disease (CVD). While glycemic control has consistently been shown to prevent microvascular complications, large randomized trials have not demonstrated the same consistent beneficial effects of intensive glycemic control in improving cardiovascular (CV) outcomes. Thus, optimal glucose control alone is not sufficient to reduce CV risk. Aggressive management of CV risk factors such as blood pressure, lipids, and body weight is also necessary. A growing body of evidence suggests that the recently available glucagon-like peptide 1 receptor (GLP-1R) agonists have beneficial CV effects beyond glucose control. Studies have demonstrated beneficial effects in the myocardium, endothelium, vasculature and various markers of cardiovascular risk such as body weight, blood pressure and dyslipidemia. Despite the growing evidence, large, randomized, blinded clinical trials with hard CV endpoints have not been performed. Most human studies have been small, and have focused on surrogate endpoints. The findings need to be confirmed by prospective, randomized cardiovascular outcomes trials. In this review we examine the GLP-1R agonist data on weight reduction, blood pressure lowering, beneficial changes in dyslipidemia, and improvements in myocardial and endothelial function. The safety as well as potential role of these agents in treatment regimens for type 2 diabetes is also addressed.

Sitagliptin, a DPP-4 inhibitor, acutely inhibits intestinal lipoprotein particle secretion in healthy humans

The dipeptidyl peptidase-4 inhibitor sitagliptin, an antidiabetic agent, which lowers blood glucose levels, also reduces postprandial lipid excursion after a mixed meal. The underlying mechanism of this effect, however, is not clear. This study examined the production and clearance of triglyceride-rich lipoprotein particles from the liver and intestine in healthy volunteers in response to a single oral dose of sitagliptin. Using stable isotope tracer techniques and with control of pancreatic hormone levels, the kinetics of lipoprotein particles of intestinal and hepatic origin were measured. Compared with placebo, sitagliptin decreased intestinal lipoprotein concentration by inhibiting particle production, independent of changes in pancreatic hormones, and circulating levels of glucose and free fatty acids. Fractional clearance of particles of both intestinal and hepatic origin, and production of particles of hepatic origin, were not affected. This pleiotropic effect of sitagliptin may explain the reduction in postprandial lipemia seen in clinical trials of this agent and may provide metabolic benefits beyond lowering of glucose levels.

Activation of glucagon-like peptide-1 receptor inhibits growth and promotes apoptosis of human pancreatic cancer cells in a cAMP-dependent manner

Glucagon-like peptide-1 (GLP-1) promotes pancreatic β-cell regeneration through GLP-1 receptor (GLP-1R) activation. However, whether it promotes exocrine pancreas growth and thereby increases the risk of pancreatic cancer has been a topic of debate in recent years. Clinical data and animal studies published so far have been controversial. In the present study, we report that GLP-1R activation with liraglutide inhibited growth and promoted apoptosis in human pancreatic cancer cell lines in vitro and attenuated pancreatic tumor growth in a mouse xenograft model in vivo. These effects of liraglutide were mediated through activation of cAMP production and consequent inhibition of Akt and ERK1/2 signaling pathways in a GLP-1R-dependent manner. Moreover, we examined GLP-1R expression in human pancreatic cancer tissues and found that 43.3% of tumor tissues were GLP-1R-null. In the GLP-1R-positive tumor tissues (56.7%), the level of GLP-1R was lower compared with that in tumor-adjacent normal pancreatic tissues. Furthermore, the GLP-1R-positive tumors were significantly smaller than the GLP-1R-null tumors. Our study shows for the first time that GLP-1R activation has a cytoreductive effect on human pancreatic cancer cells in vitro and in vivo, which may help address safety concerns of GLP-1-based therapies in the context of human pancreatic cancer.

Direct cardiovascular effects of glucagon like peptide-1

Current gold standard therapeutic strategies for T2DM target insulin resistance or β cell dysfunction as their core mechanisms of action. However, the use of traditional anti-diabetic drugs, in most cases, does not significantly reduce macrovascular morbidity and mortality. Among emerging anti-diabetic candidates, glucagon like peptide-1 (GLP-1) based therapies carry special cardiovascular implications, exerting both direct as well as indirect effects. The direct cardiovascular effects of GLP-1 and its analogs remain the focus of this review.

Effects of glucagon-like peptide-1 receptor stimulation and blockade on food consumption and body weight in rats treated with a cannabinoid CB1 receptor agonist WIN 55,212-2

Background

Glucagon-like peptide-1 (GLP-1) and endocannabinoids are involved in appetite control. Recently we have demonstrated that cannabinoid (CB)1 receptor antagonist and GLP-1 receptor agonist synergistically suppress food intake in the rat. The aim of the present study was to determine the effects of GLP-1 receptor stimulation or blockade on feeding behavior in rats treated with WIN 55,212-2, a CB1 receptor agonist.

Material/Methods

Experiments were performed on adult male Wistar rats. In the first experiment the effects of increasing doses (0.5–4.0 mg/kg) of WIN 55,212-2 injected intraperitoneally on 24-hour food consumption were tested. In further experiments a GLP-1 receptor antagonist, exendin (9-39), and WIN 55,212-2 or a GLP-1 receptor agonist, exendin-4, and WIN 55,212-2 were injected intraperitoneally at subthreshold doses (that alone did not change food intake and body weight) to investigate whether these agents may interact to affect food intake in rats.

Results

WIN 55,212-2 administered at low doses (0.5–2 mg/kg) did not markedly change 24-hour food consumption; however, at the highest dose, daily food intake was inhibited. Combined administration of WIN 55,212-2 and exendin (9-39) did not change the amount of food consumed compared to either the control group or to each agent injected alone. Combined injection of WIN 55,212-2 and exendin-4 at subthreshold doses resulted in a significant decrease in food intake and body weight in rats.

Conclusions

Stimulation of the peripheral CB1 receptor by its agonist WIN 55,212-2 can induce anorexigenic effects or potentiate, even at a subthreshold dose, the effects of exendin-4, a known anorectic agent. Hence, this dual action of the cannabinoid system should be considered in the medical use of CB1 agonists.

Insulin initiation in type 2 diabetes: what are the treatment regimen options and how can we best help patients feel empowered?

PURPOSE

This article summarizes treatment regimens and issues involved in initiating insulin therapy in type 2 diabetes (T2D). Progressive deterioration of beta-cell mass and function characterizes the course of T2D. Following diet and exercise, oral antidiabetic drugs (OADs), and incretin therapies, many patients require insulin, but initiation is often delayed until complications develop.

DATA SOURCES

Published guidelines for the management of T2D, primary and review articles, and Food and Drug Administration (FDA) prescribing information.

CONCLUSIONS

The diabetes nurse practitioner should encourage patients to initiate insulin when appropriate; patients need to know that this represents a natural step in treatment, not a personal failing. Initiation often occurs when OADs no longer confer adequate glycemic control. Treatment regimens available include once-daily basal insulin, sometimes with addition of prandial insulin, or premix/biphasic insulin. Insulin analogs confer less risk of hypoglycemia and weight gain, and greater dosing flexibility compared with conventional insulins. Insulin efficacy may be enhanced by continuing metformin and/or incretin therapies, while discontinuing other drugs as appropriate.

IMPLICATIONS FOR PRACTICE

The well-versed diabetes nurse practitioner assists the patient in selecting the most appropriate option for his/her specific needs. It is essential to help patients overcome barriers, including fears of injection pain, public embarrassment, and hypoglycemia risk.

Encapsulation of exenatide in poly-(D,L-lactide-co-glycolide) microspheres produced an investigational long-acting once-weekly formulation for type 2 diabetes

Exenatide once-weekly (EQW [2 mg s.c.]) is under development as monotherapy as an adjunct to diet and exercise or as a combination therapy with an oral antidiabetes drug(s) in adults with type 2 diabetes. This long-acting formulation contains the active ingredient of the original exenatide twice-daily (EBID) formulation encapsulated in 0.06-mm-diameter microspheres of medical-grade poly-(D,L-lactide-co-glycolide) (PLG). After mechanical suspension and subcutaneous injection by the patient, EQW microspheres hydrate in situ and adhere to one another to form an amalgam. A small amount of loosely bound surface exenatide, typically less than 1%, releases in the first few hours, whereas drug located in deeper interstices diffuses out more slowly (time to maximum, ~2 weeks). Fully encapsulated exenatide (i.e., drug initially inaccessible to diffusion) releases over a still longer period (time to maximum, ~7 weeks) as the PLG matrix hydrolyzes into lactic acid and glycolic acid, which are subsequently eliminated as carbon dioxide and water. For EQW, plasma exenatide concentrations reach the therapeutic range by 2 weeks and steady state by 6-7 weeks. This gradual approach to steady state seems to improve tolerability, as nausea is less frequent with EQW than EBID. EQW administrations may be associated with palpable skin nodules that generally resolve without further medical intervention. In comparative trials, EQW improved hemoglobin A1c more than EBID, sitagliptin, pioglitazone, or insulin glargine and reduced fasting plasma glucose more than EBID. Weight loss due to EQW or EBID was similar. EQW is the first glucose-lowering agent that is administered once weekly.

Understanding the cardiovascular effects of incretin

Cardiovascular disease (CVD), a leading cause of death in patients with diabetes mellitus, has several pathogenic mechanisms that are well established. However, the traditional hypoglycemic agents do not have proven positive effects on macrovascular disease. Novel therapeutic agents target the incretin pathway including the glucagon-like peptide 1 (GLP-1) receptor (GLP-1R) agonists and the dipeptidyl peptidase-4 inhibitors. The glucose-regulatory actions of these agents function by increasing insulin secretion and suppressing glucagon. They also act to increase weight loss not only by inhibiting gastric emptying, but also by reducing appetite. Although GLP-1 and GLP-1R agonists have demonstrated beneficial effects on myocardium and vascular endothelium including coronary and peripheral mouse vessels, they also have anti-inflammatory and anti-atherogenic actions. These agents also have positive effects on the lipid profile and blood pressure. Although these cardioprotective actions seem to be beyond the effects of glucose control and weight loss, they are mediated through GLP-1R- or GLP-1R-independent actions of cleaved GLP-1 (9-36). Larger randomized controlled trials are necessary to elucidate the clinical promise of these beneficial CVD effects.

The Current Status of Exenatide Once Weekly

Type 2 diabetes mellitus (T2DM) is a chronic, progressive metabolic disorder that is associated with long-term microvascular (retinopathy, neuropathy and nephropathy) and macrovascular (myocardial infarction, stroke, peripheral arterial disease) complications. Both the prevalence of T2DM and the cost of its long-term complications have driven the focus and emphasis on treatments aimed at reducing hyperglycemia and controlling hypertension and dyslipidemia while minimizing hypoglycemia and weight gain. Exenatide twice daily, the first GLP-1R agonist approved by the US Food and Drug Administration (FDA) and European Medicines Agency (EMEA), has been shown to reduce hemoglobin A1C, lower fasting and postprandial plasma blood glucose concentrations as well as reduce body weight without causing significant hypoglycemia. However, its current formulation requires twice daily subcutaneous injections and does not provide continuous GLP-1R activation. Therefore, a long-acting release form of exenatide has been developed for use as a once-weekly injection, providing for convenient administration and continuous GLP-1R activation. This review covers the currently published data on this new formulation including mechanism of action, pharmacokinetics, efficacy and comparison trials to other commonly used anti-diabetic agents.

Cardiovascular comorbidities of type 2 diabetes mellitus: defining the potential of glucagonlike peptide-1-based therapies

The global epidemic of diabetes mellitus (~95% type 2 diabetes) has been fueled by a parallel increase in obesity and overweight. Together, these metabolic disease epidemics have contributed to the increasing incidence and prevalence of cardiovascular disease. The accumulation of metabolic and cardiovascular risk factors in patients with type 2 diabetes--risk factors that may exacerbate one another--complicates treatment. Inadequate treatment, treatment that fails to achieve goals, increases the risk for cardiovascular morbidity and mortality. From a clinical perspective, type 2 diabetes is a cardiovascular disease, an observation that is supported by a range of epidemiologic, postmortem, and cardiovascular imaging studies. Vascular wall dysfunction, and particularly endothelial dysfunction, has been posited as a "common soil" linking dysglycemic and cardiovascular diseases. Vascular wall dysfunction promoted by environmental triggers (e.g., sedentary lifestyle) and metabolic triggers (chronic hyperglycemia, obesity) has been associated with the upregulation of reactive oxygen species and chronic inflammatory and hypercoagulable states, and as such with the pathogenesis of type 2 diabetes, atherosclerosis, and cardiovascular disease. Glucagon-like peptide-1 (GLP)-1, an incretin hormone, and synthetic GLP-1 receptor agonists represent promising new areas of research and therapeutics in the struggle not only against type 2 diabetes but also against the cardiovascular morbidity and mortality associated with type 2 diabetes. In a number of small trials in humans, as well as in preclinical and in vitro studies, both native GLP-1 and GLP-1 receptor agonists have demonstrated positive effects on a range of cardiovascular disease pathologies and clinical targets, including such markers of vascular inflammation as high-sensitivity C-reactive protein, plasminogen activator inhibitor-1, and brain natriuretic peptide. Reductions in markers of dyslipidemia such as elevated levels of triglycerides and free fatty acids have also been observed, as have cardioprotective functions. Larger trials of longer duration will be required to confirm preliminary findings. In large human trials, GLP-1 receptor agonists have been associated with significant reductions in both blood pressure and weight.

Initial combination therapy for type 2 diabetes mellitus: is it ready for prime time?

The increased prevalence of type 2 diabetes mellitus is primarily being driven by the increasing global rates of overweight/obesity. Given the magnitude of this epidemic, we can expect these metabolic abnormalities to play an increasing role in the development of cardiovascular disease. In a pathophysiologic sense, type 2 diabetes is a multiorgan, multifactorial condition, characterized by β-cell dysfunction, insulin resistance in peripheral tissues and the liver, defective incretin activity, and elevated levels of free fatty acids and proinflammatory mediators. Despite the considerable burden of disease associated with type 2 diabetes, most patients are not at, or are unable to achieve, recommended glycemic control guideline targets. In part, this is because of the relentlessly progressive nature of the disease, but it may also be attributable to the current diabetes treatment paradigm, which is characterized by ineffective lifestyle interventions, followed by monotherapy and frequent early treatment failure with prolonged periods of elevated glucose as a consequence of clinical inertia. Thus, it is most appropriate to rethink the current treatment paradigm for type 2 diabetes in the context of a more aggressive initial therapy; specifically with early initiation of combination therapy. Our current understanding of the complex pathophysiology of the disease and the progressive deterioration in glycemic control over time supports the philosophy of earlier intervention with a more comprehensive initial therapy. Thus, while control of hyperglycemia remains the paramount goal, focusing on the underlying pathophysiology of type 2 diabetes is increasingly becoming the therapeutic strategy, with the aim of potentially providing disease modification. Although this is a logical approach, it remains to be demonstrated that early combination therapy will result in disease modification in a clinical setting. Not surprisingly, the incretin-based therapies have gained a great deal of attention in the context of being a component of initial combination therapy, given their potential beneficial effects on β-cell function with lowered risk of weight gain and hypoglycemia.

[Panorama of currently available treatments for patients with type 2 diabetes. The ADA/EASD treatment algorithm. Safety and tolerability]

Type 2 diabetes is defined by chronic hyperglycemia due to at least two pathogenic alterations: resistance to the action of peripheral insulin and insufficient pancreatic insulin secretion. The pharmacological treatment of hyperglycemia in type 2 diabetes should be individualized. The choice of specific oral drug (or combination of drugs) is based on the drug's physiological mechanism, the general recommendations of the clinical practice guidelines, systematic reviews and analysis of data from clinical trials and observational studies. In general terms, clinical practice guidelines recommend starting with lifestyle modifications together with metformin, either from the outset or at 3 months; the combination should be individualized depending on the patient's profile. Therapy may be intensified every 3-6 months until targets (HbA1c 6.5-7.5%) have been reached. To chose the second drug, both its efficacy (mechanism of action) and side effects (hypoglycemic episodes, effect on weight, intestinal effects, edema/cardiac insufficiency and renal or liver insufficiency) should be considered. The controversy on the safety of oral drugs and insulin is constantly reviewed. The cardiovascular safety of intensive hyperglycemia treatment in patients with type 2 diabetes, particularly with certain agents, is an open debate. Finally, the association between insulin and cancer has aroused huge interest but the clinical significance of this association remains uncertain and further analyses are required to clarify this issue.

Further improvement in postprandial glucose control with addition of exenatide or sitagliptin to combination therapy with insulin glargine and metformin: a proof-of-concept study

OBJECTIVE

To assess the effect of a 4-week adjunctive therapy of exenatide (EXE) (5-10 microg b.i.d.) or sitagliptin (SITA) (100 mg once daily) in response to a standardized breakfast meal challenge in 48 men or women with type 2 diabetes receiving insulin glargine (GLAR) + metformin (MET).

RESEARCH DESIGN AND METHODS

This was a single-center, randomized, open-label, active comparator-controlled study with a three-arm parallel group design, consisting of: screening, 4- to 8-week run-in period, 4-week treatment period, and follow-up. In all three groups, the GLAR dose was titrated according to an algorithm (fasting blood glucose <or=100 mg/dl).

RESULTS

The unadjusted 6-h postprandial blood glucose excursion of both GLAR + MET + EXE and GLAR + MET + SITA was statistically significantly smaller than that of GLAR + MET (606 +/- 104 vs. 612 +/- 133 vs. 728 +/- 132 mg/dl/h; P = 0.0036 and 0.0008). A1C significantly decreased in all three groups (P < 0.0001), with the greatest reduction of -1.9 +/- 0.7 under GLAR + MET + EXE (GLAR + MET + SITA -1.5 +/- 0.7; GLAR + MET -1.2 +/- 0.5%-points; GLAR + MET + EXE vs. GLAR + MET P = 0.0154). The American Diabetes Association A1C target of <7.0% was reached by 80.0, 87.5, and 62.5% of subjects, respectively. GLAR + MET + EXE had the highest number (47) of adverse events, mostly gastrointestinal (56%) with one dropout. GLAR + MET or GLAR + MET + SITA only had 10 and 12 adverse events, respectively, and no dropouts. Hypoglycemia (blood glucose <50 mg/dl) rates were low and comparable among groups. Weight decreased with GLAR + MET + EXE (-0.9 +/- 1.7 kg; P = 0.0396) and increased slightly with GLAR + MET (0.4 +/- 1.5 kg; NS; GLAR + MET + EXE vs. GLAR + MET P = 0.0377).

CONCLUSIONS

EXE or SITA added to GLAR + MET further substantially reduced postprandial blood glucose excursions. Longer-term studies in a larger population are warranted to confirm these findings.

Glycaemic goals in patients with type 2 diabetes: current status, challenges and recent advances

Recommendations for the management of type 2 diabetes include rigorous control of blood glucose levels and other risk factors, such as hypertension and dyslipidaemia. In clinical practice, many patients do not reach goals for glycaemic control. Causes of failure to control blood glucose include progression of underlying pancreatic beta-cell dysfunction, incomplete adherence to treatment (often because of adverse effects of weight gain and hypoglycaemia) and reluctance of clinicians to intensify therapy. There is increasing focus on strategies that offer potential to improve glycaemic control. Structured patient education has been shown to improve glycaemic control and other cardiovascular risk factors in people with type 2 diabetes. Payment of general practitioners by results has been shown to improve glycaemic control. New classes of glucose-lowering agents have expanded the treatment options available to clinicians and patients and include the dipeptidyl peptidase 4 (DPP-4) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists. These new classes of therapy and other strategies outlined above could help clinicians to individualize treatment and help a greater proportion of patients to achieve long-term control of blood glucose.

Unraveling the science of incretin biology

Type 2 diabetes mellitus has become an enormous and worldwide healthcare problem that is almost certain to worsen. Current therapies, which address glycemia and insulin resistance, have not adequately addressed the complications and treatment failures associated with this disease. New treatments based on the incretin hormones provide a novel approach to address some components of the complex pathophysiology of type 2 diabetes. The purpose of this review is to elucidate the science of the incretin hormones and describe the incretin effect and its regulatory role in beta-cell function, insulin secretion, and glucose metabolism. The key endogenous hormones of incretin system are glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1); a key enzymatic regulator of these hormones is dipeptidyl peptidase-4, which rapidly inactivates/degrades the incretin hormones. The roles of the incretin hormones in the regulation of glucose metabolism and other related physiologic processes such as gut motility and food intake are disturbed in type 2 diabetes. These disturbances--defects in the incretin system--contribute to the pathophysiology of type 2 diabetes in manifold ways. Consequently, therapies designed to address impairments to the effects of the incretin hormones have the potential to improve glucose regulation and other abnormalities (e.g., weight gain, loss of beta-cell function) associated with type 2 diabetes.

Clinical application of incretin-based therapy: therapeutic potential, patient selection and clinical use

Incretin-based therapies address the progressive nature of type 2 diabetes mellitus, not only by addressing glucose control but also with weight-neutral (i.e., dipeptidyl peptidase-4 inhibitors sitagliptin and vildagliptin) and weight-reducing effects (i.e., glucagonlike peptide-1 [GLP-1] receptor agonists exenatide and liraglutide). Preclinical data suggest that incretin-based therapies may also preserve beta-cell function, holding promise of a truly disease-modifying therapy. This article examines clinical trial data and accepted algorithms with a view toward elucidating the application of these agents in routine clinical practice. We propose a systematic approach to treatment, addressing (1) patient selection, (2) optimal treatment combinations, and (3) timing and guidance for both initiation and intensification of therapy. The GLP-1 receptor agonists, for example, could be particularly beneficial in patients whose weight significantly increases cardiovascular risk. Early use of these agents may be effective in preventing diabetes in those at risk, or in halting or retarding disease progression in patients with frank diabetes. Additional clinical investigation will be required to test such hypotheses. Given the ever-increasing incidence of diabetes worldwide, the link between obesity and the development of type 2 diabetes, and the need for more effective, weight-focused, convenient and sustainable treatments, the data from such studies will be invaluable to further clarify the role of the incretins in the management of patients with type 2 diabetes.

Clinical application of incretin-based therapy: therapeutic potential, patient selection and clinical use

Incretin-based therapies address the progressive nature of type 2 diabetes mellitus, not only by addressing glucose control but also with weight-neutral (i.e., dipeptidyl peptidase-4 inhibitors sitagliptin and vildagliptin) and weight-reducing effects (i.e., glucagonlike peptide-1 [GLP-1] receptor agonists exenatide and liraglutide). Preclinical data suggest that incretin-based therapies may also preserve beta-cell function, holding promise of a truly disease-modifying therapy. This article examines clinical trial data and accepted algorithms with a view toward elucidating the application of these agents in routine clinical practice. We propose a systematic approach to treatment, addressing (1) patient selection, (2) optimal treatment combinations, and (3) timing and guidance for both initiation and intensification of therapy. The GLP-1 receptor agonists, for example, could be particularly beneficial in patients whose weight significantly increases cardiovascular risk. Early use of these agents may be effective in preventing diabetes in those at risk, or in halting or retarding disease progression in patients with frank diabetes. Additional clinical investigation will be required to test such hypotheses. Given the ever-increasing incidence of diabetes worldwide, the link between obesity and the development of type 2 diabetes, and the need for more effective, weight-focused, convenient and sustainable treatments, the data from such studies will be invaluable to further clarify the role of the incretins in the management of patients with type 2 diabetes.

Unraveling the science of incretin biology

Type 2 diabetes mellitus has become an enormous and worldwide healthcare problem that is almost certain to worsen. Current therapies, which address glycemia and insulin resistance, have not adequately addressed the complications and treatment failures associated with this disease. New treatments based on the incretin hormones provide a novel approach to address some components of the complex pathophysiology of type 2 diabetes. The purpose of this review is to elucidate the science of the incretin hormones and describe the incretin effect and its regulatory role in beta-cell function, insulin secretion, and glucose metabolism. The key endogenous hormones of incretin system are glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1); a key enzymatic regulator of these hormones is dipeptidyl peptidase-4, which rapidly inactivates/degrades the incretin hormones. The roles of the incretin hormones in the regulation of glucose metabolism and other related physiologic processes such as gut motility and food intake are disturbed in type 2 diabetes. These disturbances--defects in the incretin system--contribute to the pathophysiology of type 2 diabetes in manifold ways. Consequently, therapies designed to address impairments to the effects of the incretin hormones have the potential to improve glucose regulation and other abnormalities (e.g., weight gain, loss of beta-cell function) associated with type 2 diabetes.