Sitagliptin more effectively achieves a composite endpoint for A1C reduction, lack of hypoglycemia and no body weight gain compared with glipizide

Dipeptidyl peptidase IV inhibition delays developmental programming of obesity and metabolic disease in male offspring of obese mothers

Maternal obesity programs the offspring to metabolic diseases later in life; however, the mechanisms of programming are yet unclear, and no strategies exist for addressing its detrimental transgenerational effects. Obesity has been linked to dipeptidyl peptidase IV (DPPIV), an adipokine, and treatment of obese individuals with DPPIV inhibitors has been reported to prevent weight gain and improve metabolism. We hypothesized that DPPIV plays a role in maternal obesity-mediated programming. We measured plasma DPPIV activity in human maternal and cord blood samples from normal-weight and obese mothers at term. We found that maternal obesity increases maternal and cord blood plasma DPPIV activity but only in male offspring. Using two non-human primate models of maternal obesity, we confirmed the activation of DPPIV in the offspring of obese mothers. We then created a mouse model of maternal high-fat diet (HFD)-induced obesity, and found an early-life increase in plasma DPPIV activity in male offspring. Activation of DPPIV preceded the progression of obesity, glucose intolerance and insulin resistance in male offspring of HFD-fed mothers. We then administered sitagliptin, DPPIV inhibitor, to regular diet (RD)- and HFD-fed mothers, starting a week prior to breeding and continuing throughout pregnancy and lactation. We found that sitagliptin treatment of HFD-fed mothers delayed the progression of obesity and metabolic diseases in male offspring and had no effects on females. Our findings reveal that maternal obesity dysregulates plasma DPPIV activity in males and provide evidence that maternal inhibition of DPPIV has potential for addressing the transgenerational effects of maternal obesity.

Dipeptidyl peptidase-4 inhibitor sitagliptin induces vasorelaxation via the activation of Kv channels and PKA

The present study investigated the vasorelaxant effects of sitagliptin, which is a dipeptidyl peptidase-4 (DPP-4) inhibitor in aortic rings pre-contracted with phenylephrine (Phe). Sitagliptin induced vasorelaxation in a concentration-dependent manner but the inhibition of voltage-dependent K⁺ (Kv) channels by pretreatment with 4-aminopyridine (4-AP) effectively reduced this effect. By contrast, the inhibition of inward rectifier K⁺ (Kir) channels by pretreatment with barium (Ba²⁺), large-conductance calcium (Ca²⁺)-activated K⁺ (BK_Ca) channels with paxilline, and adenosine triphosphate (ATP)-sensitive K⁺ (K_ATP) channels with glibenclamide did not change this effect. Although the application of SQ 22536, which is an adenylyl cyclase inhibitor, also did not change this effect, treatment with KT 5720, a protein kinase A (PKA) inhibitor, effectively reduced the vasorelaxant effects of sitagliptin. ODQ, which is a guanylyl cyclase inhibitor, and KT 5823, a protein kinase G (PKG) inhibitor, did not impact the effect. Furthermore, neither the inhibition of Ca²⁺ channels by pretreatment with nifedipine nor the inhibition of sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pumps by pretreatment with thapsigargin changed the effect. Similarly, the effects of sitagliptin were not altered by eliminating the endothelium, by pretreatment with a nitric oxide (NO) synthase inhibitor (L-NAME), or by inhibition of small- and intermediate-conductance Ca²⁺-activated K⁺ channels (SK_Ca and IK_Ca) using apamin and TRAM-34. Taken together, these results suggest that sitagliptin induces vasorelaxation by inhibiting both membrane potential (Em)-dependent and -independent vasoconstriction and activating PKA and Kv channels independently of PKG signaling pathways, other K⁺ channels, SERCA pumps, and the endothelium.

Metformin and second- or third-generation sulphonylurea combination therapy for adults with type 2 diabetes mellitus

BACKGROUND

The number of people with type 2 diabetes mellitus (T2DM) is increasing worldwide. The combination of metformin and sulphonylurea (M+S) is a widely used treatment. Whether M+S shows better or worse effects in comparison with other antidiabetic medications for people with T2DM is still controversial.

OBJECTIVES

To assess the effects of metformin and sulphonylurea (second- or third-generation) combination therapy for adults with type 2 diabetes mellitus.

SEARCH METHODS

We updated the search of a recent systematic review from the Agency for Healthcare Research and Quality (AHRQ). The updated search included CENTRAL, MEDLINE, Embase, ClinicalTrials.gov and WHO ICTRP. The date of the last search was March 2018. We searched manufacturers' websites and reference lists of included trials, systematic reviews, meta-analyses and health technology assessment reports. We asked investigators of the included trials for information about additional trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) randomising participants 18 years old or more with T2DM to M+S compared with metformin plus another glucose-lowering intervention or metformin monotherapy with a treatment duration of 52 weeks or more.

DATA COLLECTION AND ANALYSIS

Two review authors read all abstracts and full-text articles and records, assessed risk of bias and extracted outcome data independently. We used a random-effects model to perform meta-analysis, and calculated risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, using 95% confidence intervals (CIs) for effect estimates. We assessed the certainty of the evidence using the GRADE instrument.

MAIN RESULTS

We included 32 RCTs randomising 28,746 people. Treatment duration ranged between one to four years. We judged none of these trials as low risk of bias for all 'Risk of bias' domains. Most important events per person were all-cause and cardiovascular mortality, serious adverse events (SAE), non-fatal stroke (NFS), non-fatal myocardial infarction (MI) and microvascular complications. Most important comparisons were as follows:Five trials compared M+S (N = 1194) with metformin plus a glucagon-like peptide 1 analogue (N = 1675): all-cause mortality was 11/1057 (1%) versus 11/1537 (0.7%), risk ratio (RR) 1.15 (95% confidence interval (CI) 0.49 to 2.67); 3 trials; 2594 participants; low-certainty evidence; cardiovascular mortality 1/307 (0.3%) versus 1/302 (0.3%), low-certainty evidence; serious adverse events (SAE) 128/1057 (12.1%) versus 194/1537 (12.6%), RR 0.90 (95% CI 0.73 to 1.11); 3 trials; 2594 participants; very low-certainty evidence; non-fatal myocardial infarction (MI) 2/549 (0.4%) versus 6/1026 (0.6%), RR 0.57 (95% CI 0.12 to 2.82); 2 trials; 1575 participants; very low-certainty evidence.Nine trials compared M+S (N = 5414) with metformin plus a dipeptidyl-peptidase 4 inhibitor (N = 6346): all-cause mortality was 33/5387 (0.6%) versus 26/6307 (0.4%), RR 1.32 (95% CI 0.76 to 2.28); 9 trials; 11,694 participants; low-certainty evidence; cardiovascular mortality 11/2989 (0.4%) versus 9/3885 (0.2%), RR 1.54 (95% CI 0.63 to 3.79); 6 trials; 6874 participants; low-certainty evidence; SAE 735/5387 (13.6%) versus 779/6307 (12.4%), RR 1.07 (95% CI 0.97 to 1.18); 9 trials; 11,694 participants; very low-certainty evidence; NFS 14/2098 (0.7%) versus 8/2995 (0.3%), RR 2.21 (95% CI 0.74 to 6.58); 4 trials; 5093 participants; very low-certainty evidence; non-fatal MI 15/2989 (0.5%) versus 13/3885 (0.3%), RR 1.45 (95% CI 0.69 to 3.07); 6 trials; 6874 participants; very low-certainty evidence; one trial in 64 participants reported no microvascular complications were observed (very low-certainty evidence).Eleven trials compared M+S (N = 3626) with metformin plus a thiazolidinedione (N = 3685): all-cause mortality was 123/3300 (3.7%) versus 114/3354 (3.4%), RR 1.09 (95% CI 0.85 to 1.40); 6 trials; 6654 participants; low-certainty evidence; cardiovascular mortality 37/2946 (1.3%) versus 41/2994 (1.4%), RR 0.78 (95% CI 0.36 to 1.67); 4 trials; 5940 participants; low-certainty evidence; SAE 666/3300 (20.2%) versus 671/3354 (20%), RR 1.01 (95% CI 0.93 to 1.11); 6 trials; 6654 participants; very low-certainty evidence; NFS 20/1540 (1.3%) versus 16/1583 (1%), RR 1.29 (95% CI 0.67 to 2.47); P = 0.45; 2 trials; 3123 participants; very low-certainty evidence; non-fatal MI 25/1841 (1.4%) versus 21/1877 (1.1%), RR 1.21 (95% CI 0.68 to 2.14); P = 0.51; 3 trials; 3718 participants; very low-certainty evidence; three trials (3123 participants) reported no microvascular complications (very low-certainty evidence).Three trials compared M+S (N = 462) with metformin plus a glinide (N = 476): one person died in each intervention group (3 trials; 874 participants; low-certainty evidence); no cardiovascular mortality (2 trials; 446 participants; low-certainty evidence); SAE 34/424 (8%) versus 27/450 (6%), RR 1.68 (95% CI 0.54 to 5.21); P = 0.37; 3 trials; 874 participants; low-certainty evidence; no NFS (1 trial; 233 participants; very low-certainty evidence); non-fatal MI 2/215 (0.9%) participants in the M+S group; 2 trials; 446 participants; low-certainty evidence; no microvascular complications (1 trial; 233 participants; low-certainty evidence).Four trials compared M+S (N = 2109) with metformin plus a sodium-glucose co-transporter 2 inhibitor (N = 3032): all-cause mortality was 13/2107 (0.6%) versus 19/3027 (0.6%), RR 0.96 (95% CI 0.44 to 2.09); 4 trials; 5134 participants; very low-certainty evidence; cardiovascular mortality 4/1327 (0.3%) versus 6/2262 (0.3%), RR 1.22 (95% CI 0.33 to 4.41); 3 trials; 3589 participants; very low-certainty evidence; SAE 315/2107 (15.5%) versus 375/3027 (12.4%), RR 1.02 (95% CI 0.76 to 1.37); 4 trials; 5134 participants; very low-certainty evidence; NFS 3/919 (0.3%) versus 7/1856 (0.4%), RR 0.87 (95% CI 0.22 to 3.34); 2 trials; 2775 participants; very low-certainty evidence; non-fatal MI 7/890 (0.8%) versus 8/1374 (0.6%), RR 1.43 (95% CI 0.49 to 4.18; 2 trials); 2264 participants; very low-certainty evidence; amputation of lower extremity 1/437 (0.2%) versus 1/888 (0.1%); very low-certainty evidence.Trials reported more hypoglycaemic episodes with M+S combination compared to all other metformin-antidiabetic agent combinations. Results for M+S versus metformin monotherapy were inconclusive. There were no RCTs comparing M+S with metformin plus insulin. We identified nine ongoing trials and two trials are awaiting assessment. Together these trials will include approximately 16,631 participants.

AUTHORS' CONCLUSIONS

There is inconclusive evidence whether M+S combination therapy compared with metformin plus another glucose-lowering intervention results in benefit or harm for most patient-important outcomes (mortality, SAEs, macrovascular and microvascular complications) with the exception of hypoglycaemia (more harm for M+S combination). No RCT reported on health-related quality of life.

Pharmacology of dipeptidyl peptidase-4 inhibitors and its use in the management of metabolic syndrome: a comprehensive review on drug repositioning

OBJECTIVES

Despite advances in our understanding of metabolic syndrome (MetS) and the treatment of each of its components separately, currently there is no single therapy approved to manage it as a single condition. Since multi-drug treatment increases drug interactions, decreases patient compliance and increases health costs, it is important to introduce single therapies that improve all of the MetS components.

EVIDENCE ACQUISITION

We conducted a PubMed, Scopus, Google Scholar, Web of Science, US FDA, utdo.ir and clinicaltrial.gov search, gathered the most relevant preclinical and clinical studies that have been published since 2010, and discussed the beneficial effects of dipeptidyl peptidase (DPP)-4 inhibitors to prevent and treat different constituent of the MetS as a single therapy. Furthermore, the pharmacology of DPP-4 inhibitors, focusing on pharmacodynamics, pharmacokinetics, drug interactions and their side effects are also reviewed.

RESULTS

DPP-4 inhibitors or gliptins are a new class of oral anti-diabetic drugs that seem safe drugs with no severe side effects, commonly GI disturbance, infection and inflammatory bowel disease. They increase mass and function of pancreatic β-cells, and insulin sensitivity in liver, muscle and adipose tissue. It has been noted that gliptin therapy decreases dyslipidemia. DPP-4 inhibitors increase fatty oxidation, and cholesterol efflux, and decrease hepatic triglyceride synthase and de novo lipogenesis. They delay gastric emptying time and lead to satiety. Besides, gliptin therapy has anti-inflammatory and anti-atherogenic impacts, and improves endothelial function and reduces vascular stiffness.

CONCLUSION

The gathered data prove the efficacy of DPP-4 inhibitors in managing MetS in some levels beyond anti-diabetic effects. This review could be a lead for designing new DPP-4 inhibitors with greatest effects on MetS in future. Introducing drugs with polypharmacologic effects could increase the patient's compliance and decrease the health cost that there is not in multi-drug therapy. Graphical abstract ᅟ.

NRF2 activation by antioxidant antidiabetic agents accelerates tumor metastasis

Cancer is a common comorbidity of diabetic patients; however, little is known about the effects that antidiabetic drugs have on tumors. We discovered that common classes of drugs used in type 2 diabetes mellitus, the hypoglycemic dipeptidyl peptidase-4 inhibitors (DPP-4i) saxagliptin and sitagliptin, as well as the antineuropathic α-lipoic acid (ALA), do not increase tumor incidence but increase the risk of metastasis of existing tumors. Specifically, these drugs induce prolonged activation of the nuclear factor E2-related factor 2 (NRF2)-mediated antioxidant response through inhibition of KEAP1-C151-dependent ubiquitination and subsequent degradation of NRF2, resulting in up-regulated expression of metastasis-associated proteins, increased cancer cell migration, and promotion of metastasis in xenograft mouse models. Accordingly, knockdown of NRF2 attenuated naturally occurring and DPP-4i-induced tumor metastasis, whereas NRF2 activation accelerated metastasis. Furthermore, in human liver cancer tissue samples, increased NRF2 expression correlated with metastasis. Our findings suggest that antioxidants that activate NRF2 signaling may need to be administered with caution in cancer patients, such as diabetic patients with cancer. Moreover, NRF2 may be a potential biomarker and therapeutic target for tumor metastasis.

Comparison of alogliptin and glipizide for composite endpoint of glycated haemoglobin reduction, no hypoglycaemia and no weight gain in type 2 diabetes mellitus

This was a post hoc analysis of a 2-year, double-blind study of 2639 patients with type 2 diabetes mellitus (T2DM) inadequately controlled on metformin monotherapy, which assessed achievement of a composite endpoint of sustained glycated haemoglobin (HbA1c) reduction (≤7.0% at week 104 or ≥0.5% decrease from baseline) with no weight gain and no hypoglycaemic events with alogliptin 12.5 and 25 mg daily or glipizide (≤20 mg daily), each added to metformin. With an HbA1c target of ≤7.0%, 24.2 and 26.9% of patients treated with alogliptin 12.5 and 25 mg, respectively, achieved the composite endpoint versus 10.7% of patients treated with glipizide (both p < 0.001). With a criterion of ≥0.5% decrease in HbA1c, the composite endpoint was reached in 22.5, 25.2 and 10.4% of patients treated with alogliptin 12.5 mg, alogliptin 25 mg and glipizide, respectively. Odds ratios for achieving the composite endpoint favoured alogliptin in the primary analysis set and in all subgroups of patients. Patients with T2DM failing metformin monotherapy were more likely to achieve sustained glycaemic control with no hypoglycaemia or weight gain at 2 years with alogliptin than with glipizide.

Sitagliptin: Is It Effective in Routine Clinical Practice?

Aim. The present study was conducted to determine the glycaemic effects of sitagliptin in type 2 diabetes patients. Methods. Data was collected from patient medical records of a major teaching hospital in Malaysia, from 2009 to 2012. Glycated hemoglobin (HbA1c) values prior to and up to 12 months after the initiation of sitagliptin were analysed. The change in HbA1c values was accounted for based on a generalized linear model generated using the Generalized Estimating Equations (GEE) method. Results and Discussion. Of the 457 patients, 53.6% were elderly and 81.4% were overweight. The mean HbA1c (standard deviation) before initiation of sitagliptin was 8.5 (1.4)%. This dropped to 7.7 (1.4)%, 3 to 6 months after initiation of sitagliptin, with a mean difference of 0.8% (95% confidence interval (CI): 0.7-1.0; P < 0.001). However, this value increased to 8.0 (1.7)% after 7 to 12 months on sitagliptin (P = 0.002) with a mean difference from baseline of 0.6% (95% CI: 0.4-0.7; P < 0.001). Conclusion. In routine clinical practice, sitagliptin produces a significant reduction in mean HbA1c (0.8%) within the first 6 months of use which corresponds to efficacy data obtained in controlled clinical trials. However, this reduction was lesser, 7 to 12 month later.

A Post Hoc Analysis of HbA1c, Hypoglycemia, and Weight Change Outcomes with Alogliptin vs Glipizide in Older Patients with Type 2 Diabetes

INTRODUCTION

Adverse events and complications limit the long-term use of current antidiabetic treatment options for patients with type 2 diabetes mellitus (T2DM), particularly for older adults who are often receiving therapy for other comorbid conditions. The aim of this study was to evaluate the benefits of the dipeptidyl peptidase-4 inhibitor, alogliptin, versus glipizide, a sulfonylurea, in achieving glycemic control without the risk of hypoglycemia, weight gain, or both in older patients with T2DM.

METHODS

This was an exploratory, post hoc analysis of a global, multicenter, randomized, double-blind, active-controlled study comparing alogliptin and glipizide. Patients (n = 441) aged 65-90 years with glycosylated hemoglobin (HbA1c) 6.5-9.0% who failed on diet and exercise alone or who had inadequately controlled T2DM despite oral antidiabetic monotherapy were recruited from 110 sites across 15 countries. Alogliptin 25 mg (n = 222) or glipizide 5 mg up-titrated to 10 mg (n = 219) was administered once daily for 52 weeks. Composite endpoints of HbA1c ≤7.0% coupled with the absence of hypoglycemia and weight gain, or an HbA1c reduction of ≥0.5% in the absence of hypoglycemia and weight gain, were then measured.

RESULTS

In the primary analysis, least squares mean HbA1c changes from baseline to Week 52 were similar in both the alogliptin and glipizide groups. The proportion of patients achieving HbA1c ≤7.0% without hypoglycemia or weight gain was significantly higher for alogliptin versus glipizide (24% vs 13%, p < 0.03). Patients with a baseline HbA1c of <8.0% receiving alogliptin were also more likely to achieve HbA1c ≤7.0% without hypoglycemia or weight gain than those receiving glipizide (29% vs 13%, p < 0.03).

CONCLUSION

Alogliptin demonstrated similar efficacy to glipizide in lowering HbA1c in older patients with T2DM, but with significantly more patients achieving an HbA1c ≤7.0% without hypoglycemia or an increase in body weight. These results particularly apply to patients with baseline HbA1c below 8.0%.

FUNDING

The study was sponsored by Takeda Global Research & Development Center, Inc., Deerfield, IL, and Takeda Global Research and Development Centre Ltd., London, United Kingdom.

Composite endpoints in trials of type-2 diabetes

Composite endpoints (CEPs) are being used more frequently as outcomes for trials of drugs in type-2 diabetes. We reviewed the literature to determine how CEPs have been used to date in trials of drugs for type-2 diabetes. A systematic search was undertaken on Medline, Embase and Cochrane databases and Clinicaltrials.gov for randomized controlled trials of currently marketed agents including SGLT-2 inhibitors (dapagliflozin), GLP-1 agonists (exenatide, liraglutide) and DPP-4 inhibitors (linagliptin, saxagliptin, sitagliptin and vildagliptin). CEPs used were identified as well as numbers and percentages of patients achieving each. Thirty-six studies were identified that reported results on ≥1 CEP; 15 different CEPs were reported (7 with 2 components, 8 with 3 components). All CEPs addressed goals recommended by the American Diabetes Association (ADA). All included HbA1c<7%; other endpoints measured weight, blood pressure and hypoglycaemic events. Results were obtained for CEPs from 6 months to 2 years. Rates of achieving CEPs decreased with increasing numbers of components and outcomes assessed. CEPs are becoming used as indicators of clinical outcomes in type-2 diabetes trials, but are still not common. More research is required to identify optimal CEPs. Standardization of outcomes and their reporting is needed.

Meta-analysis of the cardiovascular outcomes with dipeptidyl peptidase 4 inhibitors: validation of the current FDA mandate

BACKGROUND

Earlier meta-analyses have demonstrated a significant reduction in major adverse cardiovascular events (MACE) with dipeptidyl peptidase 4-inhibitor (DPPI) use, as compared with placebo or alternative anti-diabetic therapies. However, the large phase III/IV trials, namely SAVOR-TIMI 53 and the EXAMINE trials, failed to demonstrate any significant differences in MACE between DPPI and placebo. We aimed to perform an updated meta-analysis of randomized controlled trials (RCTs) to investigate the differences in cardiovascular death, myocardial infarction (MI), and stroke between DPPI and placebo/alternative agents.

METHODS

We searched the MEDLINE, EMBASE, and Cochrane databases for relevant phase III/IV RCTs. Unpublished trials with results available on national clinical trials registers were also included. RCTs with follow-up duration ≥24 weeks were included if they compared DPPI with placebo or an alternative anti-diabetic agent.

RESULTS

A total of 82 RCTs including 73,678 patients were included. We did not observe any significant difference in the pooled odds of cardiovascular death, MI, or stroke in the composite DPPI arm as compared with the control arm. Similarly, the pooled odds of all-cause death and MACE were statistically similar between the two groups. None of the clinical outcomes studied demonstrated evidence of statistical heterogeneity or publication bias. Due to a larger sample size and a longer duration of follow-up, both SAVOR-TIMI 53 and EXAMINE trials had a considerably larger contribution to the pooled estimates in our meta-analysis, driving the updated pooled estimates towards null for all clinical outcomes assessed.

CONCLUSIONS

DPPI use was not associated with increased incidence of cardiovascular mortality, MI, stroke, or MACE compared with placebo or alternative anti-diabetic agents.

Importance of achieving the composite endpoints in diabetes

Well-conducted randomized controlled trials are instrumental in providing vital data on safety and efficacy of new molecules under consideration for approval. However acquiring such data involves huge cost and focused scientific endeavor. Selection and reporting of endpoints of a therapy is essential to assess the effect(s) of an intervention on overall disease control and guidelines have suggested the use of composite endpoint (CEP) in clinical trial design over individual endpoints to demonstrate the compound effect. Composite endpoints have been preferred for their ability to assess the net clinical benefit of an intervention, avoid misinterpretation associated with competing risks, avoid the challenge of using a single outcome to validate the study objectives and reduce the sample size requirements in trials on patients treated for diabetes. Concerns for misinterpretation or difficulty in interpretation of trial results involving CEPs arise when differences in the components with respect to either clinical importance or event rates, or magnitude of treatment effect exist and when there's a possibility of biases due to competing risk. Suggestions for construction of composite endpoints and reporting the results of trials involving CEPs have been presented to improve the interpretations of overall effect of new interventions.

Vildagliptin more effectively achieves a composite endpoint of HbA₁c < 7.0% without hypoglycaemia and weight gain compared with glimepiride after 2 years of treatment

This post hoc analysis reports that overall proportion of patients achieving a composite endpoint of HbA1c<7.0% (<53.0 mmol/mol) without hypoglycaemia and weight gain was higher with vildagliptin than glimepiride after 2 years in type 2 diabetes patients inadequately controlled on metformin monotherapy, regardless of age and duration of diabetes.

Linagliptin is more effective than glimepiride at achieving a composite outcome of target HbA₁c < 7% with no hypoglycaemia and no weight gain over 2 years

Linagliptin treatment for 104 weeks was recently reported to achieve non-inferior glucose-lowering effects compared with glimepiride in patients with type 2 diabetes inadequately controlled with metformin. Additional analyses from this randomised, active-controlled, double-blind trial have been performed in individuals completing the study on study drug without requiring rescue therapy. In this population, significantly more patients receiving linagliptin achieved HbA1c < 7% without hypoglycaemia and without body weight gain after 2 years compared with those receiving glimepiride (54% and 23%, respectively; odds ratio of 3.9, 95% confidence interval 2.6-5.7, p < 0.0001).

Sitagliptin added to previously taken antidiabetic agents on insulin resistance and lipid profile: a 2-year study evaluation

The aim of this study was to evaluate whether the positive effects of sitagliptin on glycemic control and insulin resistance were maintained also after 2 years of therapy and whether sitagliptin could be effective also in improving lipid profile. In this randomized, double-blind, placebo-controlled trial, 205 patients with type 2 diabetes in therapy with different antidiabetic drugs were randomized to add sitagliptin 100 mg once a day or placebo to their current therapy. We evaluated at the baseline and after 6, 12, 18, and 24 months the following parameters: body mass index, glycated hemoglobin (HbA1c ), fasting plasma glucose (FPG), postprandial plasma glucose (PPG), fasting plasma insulin (FPI), homeostasis model assessment insulin resistance index (HOMA-IR), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (Tg). Sitagliptin, added to previously taken antidiabetic agents, proved to be effective in improving glycemic profile, reducing HbA1c by -17.5%, FPG by -12.7%, PPG by -20.5%. Regarding insulin resistance, sitagliptin decreased FPI by -8.3% and HOMA-IR by -20.0%, confirming that what have been already reported in short-term studies can be applied also after 2 years of treatment. Sitagliptin also reduced body weight by -4.3%. Our study also showed the positive effect of sitagliptin on lipid profile; in particular, sitagliptin decreased TC by -13.3%, LDL-C by -20.4%, and Tg by -32.3%, and also increased HDL-C by + 13.6%. Sitagliptin proved to be effective on glycemic profile and insulin resistance even after 2 years of therapy and to be effective in improving body weight and lipid profile.

A review of gliptins in 2011

INTRODUCTION

Dipeptidylpeptidase-4 (DPP-4) inhibitors offer new options for the management of type 2 diabetes (T2DM).

AREAS COVERED

This paper is an updated review, providing an analysis of both the similarities and the differences between the various compounds known as gliptins, currently used in the clinic (sitagliptin, vildagliptin, saxagliptin, alogliptin and linagliptin). This paper discusses the pharmacokinetic and pharmacodynamic characteristics of gliptins; both the efficacy and safety profiles of gliptins in clinical trials (compared with classical glucose-lowering agents), given as monotherapy or in combination, including in special populations; the positioning of DPP-4 inhibitors in the management of T2DM in recent guidelines; and various unanswered questions and perspectives.

EXPERT OPINION

The role of DPP-4 inhibitors in the therapeutic armamentarium of T2DM is evolving, as their potential strengths and weaknesses become better defined. Future critical issues may include the durability of glucose control, resulting from better β-cell protection, positive effects on cardiovascular outcomes and long-term safety issues.

The end point is just the beginning

Clinical trials to support registration of new drugs are arduous, lengthy, and expensive. Diabetes treatment trials intended to seek indications for glycemic control are facilitated by the regulatory acceptance of glycosylated hemoglobin (A1C) as a validated intermediate efficacy end point. However, A1C outcomes are not meaningful when taken outside of the context of hypoglycemia risks. Current regulatory guidance indicates that A1C efficacy end points and hypoglycemia safety end points be considered separately. A composite end point for diabetes treatment trials that integrates A1C and hypoglycemia risk into a single measure is proposed. An example would be "percentage of patients achieving A1C <7% without unacceptable hypoglycemia." The benefits and limitations of such an approach are discussed.