Factors predicting therapeutic efficacy of combination treatment with sitagliptin and metformin in type 2 diabetic patients: the COSMETIC study

Discovery of imeglimin-inspired novel 1,3,5-triazine derivatives as antidiabetic agents in streptozotocin-induced diabetes in Wistar rats via inhibition of DPP-4

Novel 1,3,5-triazine derivatives bearing oxazine have been synthesized and tested for their ability to inhibit a panel of dipeptidyl peptidase (DPP)-4, 8, and 9 enzymes. In a comparative inhibitory assay, the molecules showed potent inhibition of DPP-4 ranging from IC50 of 4.2 ± 0.30-260.5 ± 0.42 nM, with no activity against DPP-8 and DPP-9. Among the tested series, compound 8c demonstrated the strongest DPP-4 inhibitory activity with an IC50 of 4.2 ± 0.30 nM. It also showed the greatest binding affinity during docking studies with DPP-4 with a docking score of -8.956 and a glide energy of -78.546 kcal mol-1 and was found oriented in the S1 and S2 pockets of the DPP-4 active site, which is composed of the catalytic triad Ser 630, Asp 710, and His 740. The in vivo pharmacological assay revealed that compound 8c in a dose-dependent manner improved the insulin level, body weight, antioxidants, and HDL, and reduced the levels of blood glucose, LDL, and VLDL in streptozotocin-induced diabetes in Wistar rats. Our study demonstrated the discovery and development of novel 1,3,5-triazine derivatives bearing oxazine as a novel class of anti-diabetic agents via inhibition of DPP-4.

Discovery of novel 1,3,5-triazine derivatives as an antidiabetic agent in Wistar rats via inhibition of DPP-4

Aim: To develop imeglimin-inspired novel 1,3,5-triazine derivatives as antidiabetic agents. Materials & methods: These derivatives were synthesized and tested against DPP enzymes. Compound 8c was tested for in vivo antidiabetic activity in streptozotocin-induced diabetes in Wistar rats by estimating various biochemical parameters. Docking experiments were also performed. Results: Compound 8c was identified as a selective and potent DPP-4 inhibitor. It was proficiently docked into the catalytic triad of Ser 630, Asp 710 and His740 in S1 and S2 pockets of DPP-4. In experimental animals, it also showed dose-dependent improvement in blood glucose, blood insulin, bodyweight, lipid profile and kidney and liver antioxidant profiles. Conclusion: This study demonstrated the discovery of imeglimin-inspired novel 1,3,5-triazines as a potent antidiabetic agent.

The effects of macronutrients composition on hormones and substrates during a meal tolerance test in drugnaive and sitagliptin-treated individuals with type 2 diabetes: a randomized crossover study

Objective

To evaluate the effect of sitagliptin treatment in early type 2 diabetes mellitus (T2DM) and the impact of different macronutrient compositions on hormones and substrates during meal tolerance tests (MTT).

Methods

Half of the drug-naive patients with T2DM were randomly assigned for treatment with 100 mg of sitagliptin, q.d., or placebo for 4 weeks and then submitted to 3 consecutive MTT intercalated every 48 h. The MTTs differed in terms of macronutrient composition, with 70% of total energy from carbohydrates, proteins, or lipids. After 4 weeks of washout, a crossover treatment design was repeated. Both patients and researchers were blinded, and a repeated-measures ANOVA was employed for statistical analysis.

Results

Sitagliptin treatment reduced but did not normalize fasting and post-meal glucose values in the three MTTs, with lowered area-under-glucose-curve values varying from 7% to 15%. The sitagliptin treatment also improved the insulinogenic index (+86%) and the insulin/glucose (+25%), glucagon-like peptide-1/glucose (+46%) incremental area under the curves. Patients with early T2DM maintained the lowest glucose excursion after a protein- or lipid-rich meal without any major change in insulin, C-peptide, glucagon, or NEFA levels.

Conclusion

We conclude that sitagliptin treatment is tolerable and contributes to better control of glucose homeostasis in early T2DM, irrespective of macronutrient composition. The blood glucose excursion during meal ingestion is minimal in protein- or fat-rich meals, which can be a positive ally for the management of T2DM. Clinical trial no: NCT00881543.

Estimating heritability of glycaemic response to metformin using nationwide electronic health records and population-sized pedigree

Background

Variability of response to medication is a well-known phenomenon, determined by both environmental and genetic factors. Understanding the heritable component of the response to medication is of great interest but challenging due to several reasons, including small study cohorts and computational limitations.

Methods

Here, we study the heritability of variation in the glycaemic response to metformin, first-line therapeutic agent for type 2 diabetes (T2D), by leveraging 18 years of electronic health records (EHR) data from Israel’s largest healthcare service provider, consisting of over five million patients of diverse ethnicities and socio-economic background. Our cohort consists of 80,788 T2D patients treated with metformin, with an accumulated number of 1,611,591 HbA1C measurements and 4,581,097 metformin prescriptions. We estimate the explained variance of glycated hemoglobin (HbA1c%) reduction due to inheritance by constructing a six-generation population-size pedigree from national registries and linking it to medical health records.

Results

Using Linear Mixed Model-based framework, a common-practice method for heritability estimation, we calculate a heritability measure of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${h}^{2}=12.6 \%$$\end{document}h2=12.6% (95% CI, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$6.1 \%\! -\!19.1 \%$$\end{document}6.1%−19.1%) for absolute reduction of HbA1c% after metformin treatment in the entire cohort, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${h}^{2}=21.0 \%$$\end{document}h2=21.0% (95% CI, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$7.8 \%\! -\!34.4 \%$$\end{document}7.8%−34.4%) for males and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${h}^{2}=22.9 \%$$\end{document}h2=22.9% (95% CI, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$10.0 \%\! -\!35.7 \%$$\end{document}10.0%−35.7%) in females. Results remain unchanged after adjusting for pre-treatment HbA1c%, and in proportional reduction of HbA1c%.

Conclusions

To the best of our knowledge, our work is the first to estimate heritability of drug response using solely EHR data combining a pedigree-based kinship matrix. We demonstrate that while response to metformin treatment has a heritable component, most of the variation is likely due to other factors, further motivating non-genetic analyses aimed at unraveling metformin’s action mechanism.

Individuals in a population might respond differently to the same medication and this phenomenon is commonly attributed to either genes or the environment. Here, we studied the familial aspects of the response to metformin, a medication used in the treatment of type 2 diabetes. We combined information from 18 years of medical records identifying newly treated patients with type 2 diabetes with information about how the trait was inherited within their families. We calculated a metric that tells us how well differences in people’s genes account for differences in their traits, and demonstrate that although the difference in response to metformin is in part explained by the genes people with type 2 diabetes inherit, most of it is not explained by genes. This finding contributes to a better understanding of differences in metformin response and might help inform treatment in future.

Kalka and Gavrieli et al. assessed the heritability of variation in the glycaemic response to metformin by leveraging electronic health records data gathered from a large cohort of patients with diabetes and combining it with pedigree information. The authors show that although the variability in this response has a heritable component, most of it is likely non-genetic.

Optimizing the treatment of newly diagnosed type 2 diabetes mellitus with combination of dipeptidyl peptidase-4 inhibitors and metformin: An expert opinion

The expanding burden of Type 2 Diabetes Mellitus (T2DM) in today's world, with respect to incidence, prevalence, and cost incurred, is an existential risk to society. Various guidelines recommend individualization of treatment. This expert opinion aims to review the recent evidences and reach a consensus on the preferable combination therapy for use in newly diagnosed Indian T2DM patients with HbA_1C >7.5%. The core committee included seventeen diabetes specialists. Three statements were developed, discussed, and rated by specialists and recommendations were noted. Specialists were requested to rate the statements using a 9-point Likert's scale with score of 1 being “Strongly Disagree” and 9 being “Strongly Agree”. Statement-specific scores of all the specialists were added and mean score of ≥7.00 was considered to have achieved a consensus. Statements used to meet the consensus were: Statement 1. Majority of newly-diagnosed Indian diabetics have HbA_1C >7.5%; Statement 2. Patients with HbA_1C >7.5% may be initiated with dual therapy of dipeptidyl peptidase-4 inhibitors (DPP4Is) + Metformin; and Statement 3. In Indian patients with HbA_1C >7.5% at diagnosis, DPP4Is + Metformin may be considered as a first-line therapy. Literature review revealed that HbA_1C level at the time of diagnosis in majority of Indian T2DM patients is >7.5%. Consensus was reached that dual anti-diabetic therapy should be initiated in patients with HbA_1C >7.5%. DPP4Is + Metformin is the preferred cost-effective option and may be considered as a first-line therapy in Indian T2DM patients with HbA_1C >7.5% at diagnosis.

Reduction in HbA1c with SGLT2 inhibitors vs. DPP-4 inhibitors as add-ons to metformin monotherapy according to baseline HbA1c: A systematic review of randomized controlled trials

AIMS

This study compared the reduction of glycated haemoglobin (HbA1c) with sodium-glucose cotransporter type-2 inhibitors (SGLT2is) vs. dipeptidyl peptidase-4 inhibitors (DPP-4is) as add-ons to metformin in patients with type 2 diabetes mellitus (T2DM), with a specific focus on HbA1c changes according to baseline HbA1c.

MATERIALS AND METHODS

Electronic databases were scrutinized for randomized controlled trials (RCTs) evaluating the reduction of HbA1c from baseline (Δ HbA1c) with an SGLT2i or DPP-4i in patients with T2DM not well controlled by metformin monotherapy. The endpoint was Δ HbA1c using both indirect and direct comparisons.

RESULTS

Overall, Δ HbA1c was slightly greater with SGLT2is (-0.80±0.20% from 8.03±0.35%; 44 analyses, 29 RCTs, 15 with two doses, n=9321) than with DPP-4is (-0.71±0.23% from 8.05±0.43%; 61 analyses, 59 RCTs, n=17,914; P=0.0354). When the mean baseline HbA1c was<8% ([64mmol/mol] 7.79±0.15% vs. 7.71±0.23%), Δ HbA1c averaged -0.735±0.17% vs. -0.62±0.16% (P=0.0117) with SGLT2is vs. DPP-4is, respectively. However, this difference vanished when the mean baseline HbA1c was≥8% (-0.87±0.22% from 8.27±0.32% with SGLT2is vs. -0.80±0.24% from 8.35±0.33% with DPP-4is; P=0.2756). The relationship between Δ HbA1c and baseline HbA1c was only slightly stronger with SGLT2is (slope: -0.39, r²=-0.43; P<0.0001) than with DPP-4is (slope: -0.26, r²=-0.25; P<0.0001).

CONCLUSION

Because of the small difference in Δ HbA1c whatever the baseline HbA1c level with SGLT2is vs. DPP-4is as add-ons to metformin, choosing between these glucose-lowering agents in clinical practice should be based on other efficacy criteria (such as weight and blood pressure changes, cardiovascular and renal protection) or on safety profiles rather than on HbA1c levels.

Therapeutic efficacy and safety of initial triple combination of metformin, sitagliptin, and lobeglitazone in drug-naïve patients with type 2 diabetes: initial triple study

OBJECTIVE

To compare the efficacy and safety of an initial triple therapy using metformin, a dipeptidyl peptidase-4 (DPP4) inhibitor, and thiazolidinedione with a stepwise approach using sulfonylurea and metformin in new-onset, drug-naïve patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Among drug-naïve patients with 9.0%-12.0% glycated hemoglobin (HbA1c) but no hyperglycemic symptoms, 100 subjects who started triple medications (metformin 1000 mg/day, sitagliptin 100 mg/day, and lobeglitazone 0.5 mg/day) were selected as an initial triple therapy group. Age and body mass index-matched subjects (n=100) who started glimepiride (≥2 mg/day with uptitration) and metformin (≥1000 mg/day with uptitration) were selected as a conventional therapy group. We investigated changes in HbA1c level, dynamic indexes for insulin sensitivity and β-cell function, and hypoglycemia.

RESULTS

After 12 months of treatment, HbA1c levels decreased significantly in both groups: from 10.7%±1.0% to 6.7%±1.3% in the triple group, and from 10.5%±1.0% to 7.3%±1.2% in the conventional therapy group. At 12 months, achievement of the HbA1c target (<7.0%) was higher in the triple group than in the conventional group (70% vs 52%, p<0.01). Dynamic indexes related to β-cell function and insulin sensitivity improved, and albuminuria reduced significantly only in the triple group. Hypoglycemia was more common in the conventional group.

CONCLUSIONS

Initial triple combination therapy with the DPP4 inhibitor, metformin, and thiazolidinedione showed a higher achievement of the target HbA1c goal with a lower risk of hypoglycemia, better restoration of β-cell function, and multiple metabolic benefits, implying durable glycemic control. This strategy may be useful for patients presenting with type 2 diabetes and high HbA1c levels.

Effects of anagliptin on plasma glucagon levels and gastric emptying in patients with type 2 diabetes: An exploratory randomized controlled trial versus metformin

AIMS

Glucagon has an important role in glucose homeostasis. Recently, a new plasma glucagon assay based on liquid chromatography-high resolution mass spectrometry was developed. We evaluated the influence of a dipeptidyl peptidase-4 inhibitor (anagliptin) on plasma glucagon levels in Japanese patients with type 2 diabetes by using this new assay.

METHODS

Twenty-four patients with type 2 diabetes were enrolled in a prospective, single-center, randomized, open-label study and were randomly allocated to 4 weeks of treatment with metformin (1000 mg/day) or anagliptin (200 mg/day). A liquid test meal labeled with sodium [¹³C] acetate was ingested before and after the treatment period. Samples of blood and expired air were collected over 3 h. Plasma levels of glucose, glucagon, C-peptide, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) were measured, and gastric emptying was also evaluated.

RESULTS

Twenty-two patients completed the study (metformin group: n = 10; anagliptin group: n = 12). Glycemic control showed similar improvement in both groups. In the anagliptin group, there was a slight decrease of the incremental area under the plasma concentration versus time curve for glucagon after the test meal (P = 0.048). In addition, the plasma level of active GLP-1 and GIP was increased, and plasma C-peptide was also increased versus baseline. Neither anagliptin nor metformin delayed gastric emptying.

CONCLUSIONS

In patients with type 2 diabetes maintained endogenous insulin secretion, anagliptin increased the plasma level of active GLP-1 and GIP in association with a slight stimulation of insulin secretion and slight inhibition of glucagon secretion, but did not delay gastric emptying. Clinical Trial Registry: University hospital Medical Information Network UMIN000028293.

A Lower Baseline Urinary Glucose Excretion Predicts a Better Response to the Sodium Glucose Cotransporter 2 Inhibitor

We aimed to identify the clinical variables associated with a better glucose-lowering response to the sodium glucose cotransporter 2 inhibitor ipragliflozin in people with type 2 diabetes mellitus (T2DM). We especially focused on urinary glucose excretion (UGE). This was a single-arm multicenter prospective study. A total of 92 people with T2DM aged 20 to 70 years with glycosylated hemoglobin (HbA1c) levels ≥7.0% and ≤9.5% were enrolled. Ipragliflozin (50 mg) was added to the background therapy for these people for 12 weeks. After 3 months treatment with ipragliflozin, the mean HbA1c levels were decreased from 7.6% to 6.9% and 62.0% of the people reached the HbA1c target of less than 7.0% (P<0.001). In addition, body weight, blood pressure, and lipid parameters were improved after ipragliflozin treatment (all P<0.001). The baseline HbA1c (r=0.66, P<0.001) and morning spot urine glucose to creatinine ratio (r=-0.30, P=0.001) were independently associated with the HbA1c reduction. Ipragliflozin treatment for 12 weeks improves glycemic control and other metabolic parameters. A higher HbA1c and lower UGE at baseline predicts a better glucose-lowering efficacy of ipragliflozin.

Initial combination therapy with vildagliptin plus metformin in drug-naïve patients with T2DM: a 24-week real-life study from Asia

AIMS

To assess the effectiveness and safety of vildagliptin/metformin initial combination therapy in drug-naïve patients with type 2 diabetes mellitus (T2DM).

METHODS

INITIAL was a 24-week prospective, observational study in T2DM patients with glycated hemoglobin (HbA1c) ≥ 7.5%, and prescribed vildagliptin/metformin as initial combination therapy. The primary endpoint was change in HbA1c from baseline to week 24. Key secondary endpoints were HbA1c change from baseline to week 12, proportion of patients achieving HbA1c ≤7.0%, change in body weight at 12 and 24 weeks, change in HbA1c by sub-groups (baseline HbA1c, age, body mass index [BMI], dosage strength, co-morbidities) from baseline to week 24, and safety.

RESULTS

A total of 532 patients were enrolled. The mean age, HbA1c, and BMI were 49.6 ± 11.27 years, 9.3 ± 1.57%, and 26.7 ± 4.50 kg/m², respectively. Cardiovascular risk factors present at baseline were dyslipidemia (30.1%), hypertension (29.7%), and obesity (20.9%). The mean reductions in HbA1c from baseline to week 12 (-1.6 ± 1.59%) and 24 (-1.9 ± 1.70%) were statistically significant (p < .001). At 24 weeks, 39.6% of patients achieved HbA1c ≤ 7.0%, and the mean body weight reduction was -1.1 ± 2.62 kg. HbA1c reductions were consistently seen from baseline to weeks 12 and 24 in the various sub-groups. Overall, 48 (9.0%) patients reported adverse events, including one hypoglycemic episode. There were no serious adverse events or deaths.

CONCLUSIONS

Overall, in a relatively young drug-naïve T2DM Asian study population with high baseline HbA1c and often associated with cardiovascular risk factors, vildagliptin/metformin combination therapy was associated with significant and clinically relevant HbA1c reduction from baseline. This effect was seen at week 12, was maintained over 24 weeks, and was accompanied by good tolerability.

Effect of race on the glycaemic response to sitagliptin: Insights from the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS)

AIM

Pooled efficacy studies suggest that glycaemic responses to dipeptidyl-peptidase 4 inhibitors in type 2 diabetes are greatest in Asians, who may also respond better to alpha-glucosidase inhibitors. We assessed the glycaemic impact of sitagliptin by race in the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS), and whether this was enhanced in Asians with concomitant acarbose therapy.

MATERIALS AND METHODS

TECOS enrolled 14 671 patients with type 2 diabetes, cardiovascular disease and HbA1c of 48-64 mmol/mol (6.5%-8.0%), and randomized them, double-blind, to sitagliptin or placebo. There were 3265 patients (22.3%) from Asian countries. Background glucose-lowering therapies were unaltered for the first 4 months post randomization unless clinically essential, facilitating comparison of sitagliptin-associated effects in self-identified East Asian, Other (South) Asian, White Caucasian, Hispanic, Black and Indigenous groups.

RESULTS

Median baseline HbA1c by race was 54 to 57 mmol/mol (7.1%-7.4%). Mean 4-month reduction in placebo-adjusted HbA1c was greatest in East Asians (-6.6 mmol/mol [-0.60%] vs ≤6.0 mmol/mol [≤0.55%] in other groups), with significantly greater reduction vs the 2 largest groups (White Caucasians, Other Asians; P < .0001) after adjustment for covariates. After the first 4 months, East and Other Asians were more likely to initiate additional oral therapy (metformin and/or sulfonylureas) than insulin vs White Caucasians (P < .0001). Acarbose use increased in the Asian patients, but no glycaemic interaction with allocated study medication was observed (adjusted P = .12).

CONCLUSIONS

The greatest initial reduction in HbA1c with sitagliptin in the TECOS population was in East Asians. No enhanced glycaemic effect was seen when sitagliptin was given with acarbose.

Initiating therapy in patients newly diagnosed with type 2 diabetes: Combination therapy vs a stepwise approach

There is clear evidence that achieving glycaemic targets reduces the risk of developing complications as a result of type 2 diabetes (T2D). Many patients, however, continue to have suboptimal glycaemic control because of issues that include unclear advice on how to achieve these targets as well as clinical inertia. The two management approaches recommended for patients newly diagnosed with T2D are stepwise and combination therapy, each of which has advantages and disadvantages. Stepwise therapy may result in good patient adherence and allow greater individualization of therapy, and minimization of side effects and cost, and so may be appropriate for patients who are closer to goal. Stepwise therapy, however, may also lead to frequent delays in achieving glycaemic goals and longer exposure to hyperglycaemia. Combination therapy, which is now emerging as an important therapy option, has a number of potential advantages over stepwise therapy, including reduction in clinical inertia and earlier and more frequent achievement of glycated haemoglobin goals by targeting multiple pathogenic mechanisms simultaneously, which may more effectively delay disease progression. Compared with stepwise therapy, the disadvantages of combination therapy include reduced patient adherence resulting from complex, multi-drug regimens, difficulty determining the cause of poor efficacy and/or side effects, patient refusal to accept disease, and higher cost. Fixed-dose and fixed-ratio combinations are novel therapeutic approaches which may help address several issues of treatment complexity and patient burden associated with combination therapy comprising individual drugs. The choice of which drugs to administer and the decision to use stepwise vs combination therapy, however, should always be made on an individualized basis.

The Role of Glucagon in the Pathophysiology and Treatment of Type 2 Diabetes

Type 2 diabetes is a disease involving both inadequate insulin levels and increased glucagon levels. While glucagon and insulin work together to achieve optimal plasma glucose concentrations in healthy individuals, the usual regulatory balance between these 2 critical pancreatic hormones is awry in patients with diabetes. Although clinical discussion often focuses on the role of insulin, glucagon is equally important in understanding type 2 diabetes. Furthermore, an awareness of the role of glucagon is essential to appreciate differences in the mechanisms of action of various classes of glucose-lowering therapies. Newer drug classes such as dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists improve glycemic control, in part, by affecting glucagon levels. This review provides an overview of the effect of glucose-lowering therapies on glucagon on the basis of an extensive PubMed literature search to identify clinical studies of glucose-lowering therapies in type 2 diabetes that included assessment of glucagon. Clinical practice currently benefits from available therapies that impact the glucagon regulatory pathway. As clinicians look to the future, improved treatment strategies are likely to emerge that will either use currently available therapies whose mechanisms of action complement each other or take advantage of new therapies based on an improved understanding of glucagon pathophysiology.

Predictors of response to glucagon-like peptide-1 receptor agonists: a meta-analysis and systematic review of randomized controlled trials

AIMS

The aim of the present meta-analysis is the identification of the characteristics of patients, which predict the efficacy on HbA1c of glucagon-like peptide-1 receptor agonists (GLP-1 RA).

METHODS

A Medline and Embase search for "exenatide" OR "liraglutide" OR "albiglutide" OR "dulaglutide" OR "lixisenatide" was performed, collecting randomized clinical trials (duration > 12 weeks) up to September 2016, comparing GLP-1 RA at the maximal approved dose with placebo or active drugs. Furthermore, unpublished studies were searched in the www.clinicaltrials.gov register. For meta-analyses, the outcome considered were 24- and 52-week HbA1c. Separate analyses were performed, whenever possible, for subgroups of trials based on several inclusion criteria. In addition, meta-regression analyses were performed for comparisons for which 10 or more trails were available.

RESULTS

A total of 92 trials fulfilling the inclusion criteria were identified. In placebo-controlled trials (n = 41), the 24-week mean reduction of HbA1c with GLP-1 RA was - 0.75 [- 0.87; - 0.63]%. Shorter-acting molecules appear to be more effective in patients with lower fasting glucose, whereas longer-acting agents in patients with higher fasting hyperglycaemia. Obesity and duration of diabetes do not seem to moderate the efficacy of GLP-1 RA, whereas in non-Caucasians and older patients liraglutide could be less effective. At 52 weeks, only 9 placebo-controlled trials were available for preventing any reliable analyses.

CONCLUSIONS

Using a variety of approaches (meta-analyses of subgroup of trials, meta-regression, systematic review of subgroup analyses in individual trials, and meta-analyses of subgroups of patients), we identified some putative predictors of efficacy of GLP-1 RA, which deserve further investigation.

Pharmacogenetics of dipeptidyl peptidase 4 inhibitors in a Taiwanese population with type 2 diabetes

Dipeptidyl peptidase-4 (DPP-4) inhibitors are oral anti-hyperglycemic drugs enabling effective glycemic control in type 2 diabetes (T2D). Despite DPP-4 inhibitors' advantages, the patients' therapeutic response varies. In this retrospective cohort study, 171 Taiwanese patients with T2D were classified as sensitive or resistant to treatment based on the mean change in HbA1c levels. Using an assumption-free genome-wide association study, 45 single nucleotide polymorphisms (SNPs) involved in the therapeutic response to DPP-4 inhibitors (P < 1 × 10-4) were identified at or near PRKD1, CNTN3, ASK, and LOC10537792. A SNP located within the fourth intron of PRKD1 (rs57803087) was strongly associated with DPP-4 inhibitor response (P = 3.2 × 10-6). This is the first pharmacogenomics study on DPP-4 inhibitor treatment for diabetes in a Taiwanese population. Our data suggest that genes associated with β-cell function and apoptosis are involved in the therapeutic effect of DPP-4 inhibitors, even in the presence of additional oral anti-diabetic drugs. Our findings provide information on how genetic variants influence drug response and may benefit the development of personalized medicine.

The Glucose-lowering Efficacy of Sitagliptin in Obese Japanese Patients with Type 2 Diabetes

Objective Dipeptidyl peptidase-4 (DPP-4) inhibitors are the most frequently prescribed oral hypoglycemic agents in Japan. Although a relationship between the efficacy of DPP-4 inhibitors and the body mass index (BMI) has been reported, this relationship is controversial. We investigated whether the BMI value affects the glucose-lowering efficacy of sitagliptin in obese Japanese patients with type 2 diabetes. Methods One hundred sixty-two outpatients with inadequate glycemic control were divided into four groups based on their baseline BMI values. They were then treated with sitagliptin (a DPP-4 inhibitor) for 3 months and followed-up for 12 months. Results Sitagliptin significantly reduced the hemoglobin A1c level (HbA1c: -0.71±0.55%) after 3 months, and continued to reduce the HbA1c level until 12 months. There was no significant difference in the efficacy of sitagliptin among the four BMI groups. A multiple linear regression analysis indicated that the factors contributing to the change in the HbA1c level were the baseline level of HbA1c and the homeostasis model assessment of β-cell function (HOMA-β). In terms of the relationship between the baseline BMI value and the efficacy of sitagliptin treatment, the number of patients who responded to sitagliptin treatment after 3 months was lowest in the group of patients with the highest BMI values. A multiple logistic regression analysis revealed that the baseline HOMA-β function and HbA1c level and a baseline BMI value of ≥30 kg/m² significantly contributed to the response to sitagliptin treatment. Conclusion The results indicated that sitagliptin treatment was effective in controlling glucose metabolism disorder in obese Japanese patients with type 2 diabetes. However, the efficacy of sitagliptin treatment might be attenuated in severely obese patients, such as those with a BMI value of ≥30 kg/m².

Efficacy and safety of initial combination therapy with gemigliptin and metformin compared with monotherapy with either drug in patients with type 2 diabetes: A double-blind randomized controlled trial (INICOM study)

BACKGROUND

Gemigliptin is a new dipeptidyl peptidase-IV inhibitor. We investigated the efficacy and safety of initial combination therapy with gemigliptin and metformin compared with monotherapy with either drug in patients with type 2 diabetes (T2D).

METHODS

A total of 433 T2D patients with a glycosylated haemoglobin (HbA1c) level of 7.5% to 11.0% and a fasting plasma glucose (FPG) concentration <270 mg/dL were randomly assigned to 3 groups: (1) gemigliptin 50 mg qd + metformin 1000 to 2000 mg qd (titrated individually), (2) gemigliptin 50 mg qd, or (3) metformin 1000 to 2000 mg qd. The primary end-point was the change in HbA1c level after 24 weeks. Secondary end-points were the changes in FPG, insulin, proinsulin and C-peptide levels. The percentages of responders who achieved an HbA1c level <7% (or <6.5%) were compared between treatment groups.

RESULTS

Baseline HbA1c levels were 8.7% in all groups. The mean changes in HbA1c level from baseline to week 24 were -2.06%, -1.24% and -1.47% in the combination, gemigliptin monotherapy and metformin monotherapy groups, respectively. The 95% confidence intervals for between-group differences in HbA1c changes were -1.02 to -0.63 in the combination group vs the gemigliptin group and -0.82 to -0.41 vs the metformin group, which confirmed the superiority of combination therapy. A significantly higher percentage of patients in the combination therapy group reached the target HbA1c level <7% (or <6.5%) compared with the monotherapy groups. No severe side effects were observed.

CONCLUSIONS

In T2D patients, the initial combination of gemigliptin and metformin had superior efficacy without safety concerns compared with monotherapy with either drug.

Predictive Factors for the Therapeutic Response to Concomitant Treatment with DPP-4 Inhibitors in Type 2 Diabetes with Short-Term Follow-Up

Objectives To evaluate the efficacy and predictive factors of Dipeptidyl peptidase-4 (DPP-4) inhibitors in type 2 diabetes mellitus (T2DM) patients who were not well controlled with other oral antidiabetic drugs or insulin in real clinical practice. Methods From December 2012 to January 2014, retrospective longitudinal observation study was conducted for patients with T2DM who were not reached a glycemic target (glycated hemoglobin [HbA1c] &gt; 6.5%) with other oral antidiabetic drugs or insulins. Type 1 diabetes or other types of diabetes were excluded. Responders were eligible with decreased HbA1c from baseline for more than 5% during follow up period. Results Of total 135 T2DM patients having an average 9.0 months follow-up period, 84 (62.2%) of patients were responder to DPP-4 inhibitors. After concomitant treatment with DPP-4 inhibitors, patients had a mean decrease in HbA1c of 0.69 ± 1.3%, fasting plasma glucose of 13 ± 52 ㎎/㎗, and postprandial plasma glucose of 29 ± 85 ㎎/㎗ from baseline (all P&lt; 0.05). Independent predictive factor for an improvement of glycemic control with DPP-4 inhibitors was higher baseline HbA1c (odds ratio 2.07 with 95% confidence interval 1.15–3.72) compared with non-responders. Conclusions A clinical meaningful improvement in glycemic control was seen when DPP-4 inhibitors were added to other anti-diabetic medications in patients with T2DM regardless of age, duration of T2DM, type of combination treatment regimen. Patients who had higher HbA1c were more easily respond to DPP-4 inhibitors treatment in short-term follow-up period.

Predictors of efficacy of GLP-1 agonists and DPP-4 inhibitors: A systematic review

AIMS

To identify the determinants of efficacy of glucagon-like peptide-1 receptor agonists (GLP-1A) and dipeptidyl peptidase-4 inhibitors (DPP-4I).

METHODS

MEDLINE and EMBASE were searched between 01/01/2011 and 15/08/2014 for randomized controlled trials of 12-52weeks' duration, which reported the change in glycated hemoglobin (HbA1c) from baseline as the primary end point, and reported data about predictors of efficacy of incretins.

RESULTS

Among 4172 studies found, 77 studies reported data on baseline HbA1c, age, sex, ethnicity, body mass index (BMI), and history of diabetes in relation to change in HbA1c. For DPP-4I, 37 out of 47 studies reported a greater decrease in HbA1c among patients with higher baseline HbA1c. Most DPP-4I studies reported no variation in efficacy in regard to demographic characteristics or BMI. Among 17 studies reporting on GLP-1A, baseline higher HbA1c was reported as predictive of a greater response in 7 out of 9 studies; 13 studies reported data about other factors, without consistent findings.

CONCLUSIONS

Current evidence suggests that higher baseline HbA1c is associated with a greater efficacy of both DPP-4I and GLP-1A therapies in lowering HbA1c. The roles of other potential predictors are less consistent across studies and require further investigation.

Teneligliptin, a Dipeptidyl Peptidase-4 Inhibitor, Improves Early-Phase Insulin Secretion in Drug-Naïve Patients with Type 2 Diabetes

Introduction

It remains unknown whether dipeptidyl peptidase-4 (DPP-4) inhibitors improve early-phase insulin secretion in Japanese patients with type 2 diabetes (T2D), a disease characterized by impaired insulin secretion. We investigated the changes in insulin secretion before and after treatment with the DPP-4 inhibitor teneligliptin in patients with T2D with a low insulinogenic index (IGI) determined by the oral glucose tolerance test (OGTT).

Methods

An open-label, prospective clinical study was conducted. Thirteen drug-naïve patients (mean age 55.5 ± 3.9 years) with T2D underwent OGTT before and after teneligliptin 20 mg/day monotherapy. Plasma levels of glucose (PG), insulin, and C-peptide were measured at 0, 30, 60, 90, and 120 min after glucose loading in the OGTT. Homeostasis model assessment (HOMA)-β, IGI, and the total or incremental area under the curve (AUC) for PG and insulin were measured. AUC_120min for the secretory units of islets in transplantation (SUIT) index was also measured.

Results

HbA1c significantly decreased from 8.3 ± 0.4 % at baseline to 6.3 ± 0.2 % after 12 weeks of teneligliptin treatment (p < 0.05). Incremental AUC_120min PG also significantly decreased, and β-cell function assessed by IGI_30min, AUC_120min insulin, and the AUC_120min SUIT index significantly increased (0.16 ± 0.05 vs. 0.28 ± 0.06, 2692 ± 333 µU·2h/mL vs. 3537 ± 361 µU·2h/mL, and 4261 ± 442 vs. 8290 ± 1147, respectively; all p < 0.05). HOMA-β was unchanged. The reduction in incremental AUC_120min PG was significantly associated with the augmentation of IGI_30min and the AUC_120min SUIT index. No severe adverse events were observed.

Conclusions

Twelve weeks of teneligliptin treatment improved IGI_30min, AUC_120min, and the SUIT index in drug-naïve Japanese patients with T2D.

Identification of predictors of response to basal insulin and DPP4 inhibitors in patients with type 2 diabetes failing to other therapies

AIM

Basal insulin and DPP4 inhibitors are both possible options in patients with type 2 diabetes failing to oral drugs. The identification of clinical predictors of success with either one of the two approaches could be of help in personalizing therapy.

METHODS

The retrospective study was performed on a consecutive series of patients with type 2 diabetes (n = 1,002) failing to at least one oral agent, who had been prescribed either basal insulin or DPP4 inhibitors in the previous 2 years, with a duration of follow-up of at least 6 months. Clinical predictors of success after 6 months from the beginning of second-line treatment were identified in the cohort.

RESULTS

Among patients receiving a prescription of basal insulin, the proportion of therapeutic success at 6 months was 26.5 %. At multivariate analysis, a higher age and BMI, and a lower duration of diabetes were associated with success, as well as treatment with acarbose; conversely, a history of ischemic heart disease was associated with failure. Prescription of DPP4 inhibitors produced a therapeutic success in 24.8 % of cases. At multivariate analysis, success was associated with a lower baseline HbA1c and duration of diabetes, and a higher BMI and comorbidity; in addition, a lower success rate was found in women after adjusting for other confounders.

CONCLUSIONS

The present data support the view that insulin treatment is preferable in patients with severe hyperglycemia, failing to one or more drugs, whereas DPP4 inhibitors appear to be more useful in those with comorbid conditions.

Predictive Factors for Efficacy of Dipeptidyl Peptidase-4 Inhibitors in Patients with Type 2 Diabetes Mellitus

BACKGROUND

Predictive factors for the efficacy of dipeptidyl peptidase-4 (DPP-4) inhibitors for lowering glycosylated hemoglobin (HbA1c) remain unclear in patients with type 2 diabetes mellitus. The aim of this study is therefore to clarify predictive factors of the efficacy of DPP-4 inhibitors for lowering HbA1c after 12 months of treatment.

METHODS

A total of 191 consecutive type 2 diabetic patients (male sex 55%, mean age, 68.3±35.8 years), who had been treated with DPP-4 inhibitors for 12 months, were enrolled in this study and evaluated retrospectively.

RESULTS

After 12 months of DPP-4 inhibitor treatment, random blood glucose level, and HbA1c level, decreased from 167±63 to 151±49 mg/dL (P<0.01), and from 7.5%±1.3% to 6.9%±0.9% (P<0.01) respectively, without severe side effects. Multiple regression analysis showed that predictors of DPP-4 inhibitor treatment efficacy in lowering HbA1c level after 12 months were a decrease in HbA1c level after 3 months of treatment, a high baseline HbA1c level, a low baseline body mass index, and the absence of coronary artery disease.

CONCLUSION

Most suitable candidates for treatment with DPP-4 inhibitors are diabetics who are not obese and do not have coronary artery disease. In addition, long-term efficacy of DPP-4 inhibitors can be predicted by decrement of HbA1c after 3 months of treatment.

Four-Year Durability of Initial Combination Therapy with Sitagliptin and Metformin in Patients with Type 2 Diabetes in Clinical Practice; COSMIC Study

OBJECTIVES

We investigated the efficacy of initial combination therapy with sitagliptin and metformin in patients with type 2 diabetes for 4 years in clinical practice.

METHODS

Between 2009 and 2010, we reviewed 1,178 patients with type 2 diabetes (HbA1c ≥7.5% or 58 mmol/mol) prescribed initial combination therapy with sitagliptin and metformin. After excluding 288 patients without a second follow-up, 890 individuals (age, 58.0 ± 12.5 years; BMI, 25.4 ± 3.5 kg/m2; HbA1c, 8.6 ± 1.1%) were followed up with every 3-6 months for 4 years. Homeostasis model assessments for insulin resistance and β-cell function (HOMA-β) were recorded at baseline. The response criterion was HbA1c reduction by ≥0.8% from baseline or attainment of the target HbA1c (≤7.0% or 53 mmol/mol). At the end of every year of treatment, changes in HbA1c from the baseline were assessed.

RESULTS

After 1 year, 72.2% of patients with initial combination therapy had responded, defined as HbA1c reduction ≥0.8% or attainment of the target HbA1c ≤7.0%. After 4 years, 35.4% of the patients still showed a response, with an HbA1c level of 7.0 ± 0.9%. A high HbA1c level at baseline was the most significant independent predictor of the long-term response (P<0.001). In addition, low HOMA-β was a significant predictor of a greater reduction in HbA1c. This treatment was generally well tolerated over the 4-year follow-up period, without any serious adverse events.

CONCLUSIONS

This real-world follow-up study shows a persistent glucose-reducing effect of initial combination therapy with sitagliptin and metformin for up to 4 years.

Anagliptin and sitagliptin as add-ons to metformin for patients with type 2 diabetes: a 24-week, multicentre, randomized, double-blind, active-controlled, phase III clinical trial with a 28-week extension

We conducted a 24-week, multicentre, double-blind, randomized study with a 28-week extension to compare the efficacy and safety of anagliptin and sitagliptin as an add-on to metformin in patients with type 2 diabetes. Patients inadequately controlled on metformin were randomized to either anagliptin (100 mg twice daily, n = 92) or sitagliptin (100 mg once daily, n = 88). The primary endpoint was the change in glycated haemoglobin (HbA1c) from baseline to week 24. The mean changes in HbA1c were -0.85 ± 0.70% (p < 0.0001) for anagliptin and -0.83 ± 0.61% (p < 0.0001) for sitagliptin, with a mean difference of -0.02% (95% confidence interval of difference, -0.22 to 0.18%). In both groups, the fasting proinsulin : insulin ratio significantly decreased from baseline, with improved insulin secretion. Safety profiles were similar in each group. In conclusion, the non-inferiority of the efficacy of anagliptin to sitagliptin as an add-on therapy was established with regard to efficacy and safety.

Optimal candidates for the switch from glimepiride to sitagliptin to reduce hypoglycemia in patients with type 2 diabetes mellitus

BACKGROUND

Sitagliptin is a novel antidiabetic agent with a low risk for hypoglycemia. We investigated the efficacy and safety of sitagliptin when patients switched from a sulfonylurea to sitagliptin and identified good candidates for the switch.

METHODS

Sixty-one patients with type 2 diabetes switched from glimepiride with metformin to sitagliptin with metformin due to clinical hypoglycemia. Serum glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), and 2-hour postprandial plasma glucose (2h-PPG) before and 12 and 24 weeks after the drug switch were checked.

RESULTS

HbA1c and FPG levels did not change 12 or 24 weeks after the switch; however, the 2h-PPG level decreased from 218.0±67.5 mg/dL at baseline to 197.1±69.9 mg/dL at 12 weeks and 192.3±67.4 mg/dL at 24 weeks after switching drugs (P=0.045, P=0.018, respectively). All but one patient no longer experienced hypoglycemia after discontinuing glimepiride. In a multivariate logistic regression analysis, a high homeostasis model assessment of insulin resistance and low baseline HbA1c level were independent predictors of an HbA1c ≤7% after switching to sitagliptin.

CONCLUSION

Glycemic control was not aggravated in patients 24 weeks after the drug switch, and symptomatic hypoglycemia decreased significantly. Patients with dominant insulin resistance may be good candidates for switching from a sulfonylurea to sitagliptin to reduce hypoglycemia.

Initial combination of linagliptin and metformin compared with linagliptin monotherapy in patients with newly diagnosed type 2 diabetes and marked hyperglycaemia: a randomized, double-blind, active-controlled, parallel group, multinational clinical trial

AIMS

To evaluate glucose-lowering treatment strategies with linagliptin and metformin in people with newly diagnosed type 2 diabetes and marked hyperglycaemia, a prevalent population for which few dedicated studies of oral antidiabetes drugs have been conducted.

METHODS

A total of 316 patients, with type 2 diabetes diagnosed for ≤12 months and with glycated haemoglobin (HbA1c) concentration in the range 8.5-12.0%, were randomized 1:1 to double-blind, free-combination treatment with linagliptin 5 mg once daily and metformin twice daily (uptitrated to 2000 mg/day maximum) or to linagliptin monotherapy. The primary endpoint was change in HbA1c concentration from baseline at week 24 (per-protocol completers' cohort: n = 245).

RESULTS

The mean (standard deviation) age and HbA1c at baseline were 48.8 (11.0) years and 9.8 (1.1)%, respectively. At week 24, the mean ± standard error (s.e.) HbA1c decreased from baseline by -2.8 ± 0.1% with linagliptin/metformin and -2.0 ± 0.1% with linagliptin; a treatment difference of -0.8% (95% confidence interval -1.1 to -0.5; p <0.0001). Similar results were observed in a sensitivity analysis based on intent-to-treat principles: adjusted mean ± s.e. changes in HbA1c of -2.7 ± 0.1% and -1.8 ± 0.1%, respectively; treatment difference of -0.9% (95% CI -1.3 to -0.6; p <0.0001). A treatment response of HbA1c <7.0% was achieved by 61 and 40% of patients in the linagliptin/metformin and linagliptin groups, respectively. Few patients experienced drug-related adverse events (8.8 and 5.7% of patients in the linagliptin/metformin and linagliptin groups, respectively). Hypoglycaemia occurred in 1.9 and 3.2% of patients in the linagliptin/metformin and linagliptin groups, respectively (no severe episodes). Body weight decreased significantly with the combination therapy (-1.3 kg between-group difference; p =0.0033).

CONCLUSIONS

Linagliptin in initial combination with metformin in patients with newly diagnosed type 2 diabetes and marked hyperglycaemia, an understudied group, elicited significant improvements in glycaemic control with a low incidence of hypoglycaemia, weight gain or other adverse effects. These results support early combination treatment strategies and suggest that newly diagnosed patients with marked hyperglycaemia may be effectively managed with oral, non-insulin therapy.

The Effect of DPP-4 Inhibitors on Metabolic Parameters in Patients with Type 2 Diabetes

BACKGROUND

We evaluated the effects of two dipeptidyl peptidase-4 (DPP-4) inhibitors, sitagliptin and vildagliptin, on metabolic parameters in patients with type 2 diabetes mellitus.

METHODS

A total of 170 type 2 diabetes patients treated with sitagliptin or vildagliptin for more than 24 weeks were selected. The patients were separated into two groups, sitagliptin (100 mg once daily, n=93) and vildagliptin (50 mg twice daily, n=77). We compared the effect of each DPP-4 inhibitor on metabolic parameters, including the fasting plasma glucose (FPG), postprandial glucose (PPG), glycated hemoglobin (HbA1c), and glycated albumin (GA) levels, and lipid parameters at baseline and after 24 weeks of treatment.

RESULTS

The HbA1c, FPG, and GA levels were similar between the two groups at baseline, but the sitagliptin group displayed a higher PPG level (P=0.03). After 24 weeks of treatment, all of the glucose-related parameters were significantly decreased in both groups (P=0.001). The levels of total cholesterol and triglycerides were only reduced in the vildagliptin group (P=0.001), although the sitagliptin group received a larger quantity of statins than the vildagliptin group (P=0.002).The mean change in the glucose- and lipid-related parameters after 24 weeks of treatment were not significantly different between the two groups (P=not significant). Neither sitagliptin nor vildagliptin treatment was associated with a reduction in the high sensitive C-reactive protein level (P=0.714).

CONCLUSION

Vildagliptin and sitagliptin exert a similar effect on metabolic parameters, but vildagliptin exerts a more potent beneficial effect on lipid parameters.

Sitagliptin Improves the Impaired Acute Insulin Response during a Meal Tolerance Test in Japanese Patients with Type 2 Diabetes Mellitus: A Small-Scale Real-World Study

INTRODUCTION

Several studies have shown that dipeptidyl peptidase-4 (DPP-4) inhibitors improve insulin secretion during oral glucose tolerance tests. However, the effects of DPP-4 inhibitors on impaired acute insulin responses in the postprandial state in real-world settings are unknown. Therefore, we evaluated the effects of sitagliptin on the acute insulin responses in Japanese patients with type 2 diabetes mellitus (T2DM) using meal tolerance tests.

METHODS

Twenty-one patients with T2DM were given a test meal (460 kcal), and plasma glucose and insulin were measured at 0, 30, 60, 120, and 180 min after the meal. The insulinogenic index of all of these patients was below 43.2. The postprandial profiles were assessed at baseline and after 3 months of treatment with 50 mg/day sitagliptin after a meal (n = 11) or were untreated (control group; n = 10). This study was a prospective, open-label, non-blinded, non-randomized, clinical study.

RESULTS

Sitagliptin significantly decreased the plasma glucose levels at 60, 120, and 180 min, and significantly increased the plasma insulin levels at 0 and 30 min. There were no significant changes in glucose or insulin in the control group. The insulinogenic index increased significantly in the sitagliptin group compared with the control group (+16.7 vs. +0.1, P < 0.005). However, homeostasis model assessment of insulin resistance and the insulin sensitivity index were not significant different between the two groups.

CONCLUSION

Administration of sitagliptin at 50 mg/day after a meal improved the impaired acute insulin response and suppressed postprandial hyperglycemia. Whereas the study is rather small and the design is suboptimal as it is not randomized and not blinded, these results suggest that sitagliptin is effective in Japanese patients with T2DM, many of whom display impaired acute insulin responses after a meal.

Assessment of pancreatic β-cell function: review of methods and clinical applications

Type 2 diabetes mellitus (T2DM) is characterized by a progressive failure of pancreatic β-cell function (BCF) with insulin resistance. Once insulin over-secretion can no longer compensate for the degree of insulin resistance, hyperglycemia becomes clinically significant and deterioration of residual β-cell reserve accelerates. This pathophysiology has important therapeutic implications. Ideally, therapy should address the underlying pathology and should be started early along the spectrum of decreasing glucose tolerance in order to prevent or slow β-cell failure and reverse insulin resistance. The development of an optimal treatment strategy for each patient requires accurate diagnostic tools for evaluating the underlying state of glucose tolerance. This review focuses on the most widely used methods for measuring BCF within the context of insulin resistance and includes examples of their use in prediabetes and T2DM, with an emphasis on the most recent therapeutic options (dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists). Methods of BCF measurement include the homeostasis model assessment (HOMA); oral glucose tolerance tests, intravenous glucose tolerance tests (IVGTT), and meal tolerance tests; and the hyperglycemic clamp procedure. To provide a meaningful evaluation of BCF, it is necessary to interpret all observations within the context of insulin resistance. Therefore, this review also discusses methods utilized to quantitate insulin-dependent glucose metabolism, such as the IVGTT and the euglycemic-hyperinsulinemic clamp procedures. In addition, an example is presented of a mathematical modeling approach that can use data from BCF measurements to develop a better understanding of BCF behavior and the overall status of glucose tolerance.

Impact of three oral antidiabetic drugs on markers of β-cell function in patients with type 2 diabetes: a meta-analysis

Background

The effect of metformin, pioglitazone and sitagliptin on β-cell function in the treatment of type 2 diabetes is controversial. Therefore, we performed a systematic review and meta-analysis to obtain a better understanding in the β-cell effects of metformin, pioglitazone and sitagliptin.

Methods

We searched Pubmed and the Cochrane Center Register of Controlled Trials to identify relevant studies. Trials investigating effects of sitagliptin, metformin or pioglitazone on β-cell function were identified. The primary outcomes were homeostasis model assessment of β-cells (HOMA-β) and proinsulin/insulin ratio (PI/IR). Secondary outcome was hemoglobin A1c level. We used version 2 of the Comprehensive Meta Analysis software for all statistical analyses.

Results

Metformin monotherapy was more effective than sitagliptin in improving HOMA-β (18.01% (95% CI 11.09% to 24.94%) vs. 11.29% (95% CI 9.21% to 13.37%), P = 0.040) and more effective (−0.137 (95% CI −0.082 to −0.192)) than both sitagliptin (−0.064 (95% CI −0.036 to −0.092), P = 0.019) and pioglitazone (−0.068 (95% CI −0.044 to −0.093), P = 0.015) in decreasing PI/IR. Metformin and sitagliptin combined (40.23% (95%CI 32.30% to 48.16%)) were more effective than sitagliptin and pioglitazone (11.82% (95% CI 6.61% to 17.04%), P = 0.000) and pioglitazone and metformin(9.81% (95% CI 1.67% to 17.95%), P = 0.022) in improving HOMA-β and decreasing PI/IR (−0.177 (95% CI −0.118 to −0.237); −0.080 (95% CI −0.045 to −0.114), P = 0.007; −0.038 (95% CI, −0.005 to 0.071), P = 0.023).

Limitations

The included RCTs were of short duration (12–54 weeks). We could not determine long term effects on β-cells.

Conclusions

Metformin improves β-cell function more effectively than pioglitazone or sitagliptin in type 2 diabetes patients. Metformin and sitagliptin improved HOMA-β and PI/IR more than other combinations.

Predictive factors of durability to sitagliptin: Slower reduction of glycated hemoglobin, older age and higher baseline glycated hemoglobin

Aims/Introduction

The goal of the present study was to evaluate predictive factors for good efficacy and durability to sitagliptin with ongoing metformin or metformin plus glimepiride therapy in a real practice situation. The present observational study was carried out over a 60‐week period and involved Korean patients with type 2 diabetes mellitus.

Materials and Methods

A total of 100 mg of sitagliptin were added once daily to the two most popular therapy regimens (group 1: metformin, group 2: metformin plus glimepiride). Before adding sitagliptin, mean initial glycated hemoglobin (HbA1c) levels were 7.8% (62 mmol/mol) and mean diabetes duration was 8.3 years.

Results

After 60 weeks, the mean change in HbA1c from baseline was −0.9% (−10 mmol/mol) in group 1 and −1.0% (−11 mmol/mol) in group 2. Decreased HbA1c levels were significantly associated with higher initial HbA1c and lower log‐transformed C‐peptide levels in a multivariate regression analysis. Logistic regression analysis showed that a sustained reduction in HbA1c levels after 12 weeks was significantly associated with older age (≥60 years), higher baseline HbA1c (group 1 ≥ 7.0% [53 mmol/mol], group 2 ≥ 7.5% [58 mmol/mol]) and slower reduction of HbA1c (ΔHbA1c <1.0% [11 mmol/mol]) in group 1 and group 2. In group 2, a higher ratio of reduction of postprandial glucose/reduction of fasting plasma glucose (ΔPPG/ΔFPG) during 12 weeks was also associated with a sustained reduction in HbA1c levels after 12 weeks.

Conclusions

The effects of sitagliptin lasted more than 12 weeks in older patients with a higher baseline HbA1c, and slower reduction of HbA1c during 12 weeks.

A review of sitagliptin with special emphasis on its use in moderate to severe renal impairment

Sitagliptin is the first dipeptidylpeptidase-4 inhibitor to be used in the management of type 2 diabetes. It is widely used as an add-on therapy to ongoing management or as monotherapy where it is deemed necessary. It has been found to be beneficial in improving β-cell function and glycemic control, and also is used in special circumstances like chronic kidney disease, with appropriate dose reductions. Overall, cardiovascular outcomes are no different from other oral hypoglycemic agents. In this review article we have summarized all the previous studies relevant to sitagliptin use in clinical practice and emphasized its use in various stages of chronic kidney disease.

Clinical characteristics of the responders to dipeptidyl peptidase-4 inhibitors in Korean subjects with type 2 diabetes

We investigated characteristics associated with the efficacy of dipeptidyl peptidase-4 inhibitors (DPP4i) in Korean patients with type 2 diabetes. We reviewed medical records of 477 patients who had taken sitagliptin or vildagliptin longer than 40 weeks. Response to DPP4i was evaluated with HbA1c change after therapy (ΔHbA1c). The Student's t-test between good responders (GR: ΔHbA1c > 1.0%) and poor responders (PR: ΔHbA1c < 0.5%), a correlation analysis among clinical parameters, and a linear multivariate regression analysis were performed. The mean age was 60 yr, duration of diabetes 11 yr and HbA1c was 8.1%. Baseline fasting plasma glucose (FPG), HbA1c, C-peptide, and creatinine were significantly higher in the GR compared to the PR. Duration of diabetes, FPG, HbA1c, C-peptide and creatinine were significantly correlated with ΔHbA1c. In the multivariate analysis, age (r(2) = 0.006), duration of diabetes (r(2) = 0.019), HbA1c (r(2) = 0.296), and creatinine levels (r(2) = 0.024) were independent predictors for the response to DPP4i. Body mass index and insulin resistance were not associated with the response to DPP4i. In conclusion, better response to DPP4i would be expected in Korean patients with type 2 diabetes who have higher baseline HbA1c and creatinine levels with shorter duration of diabetes.