Retrospective analysis on the efficacy, safety and treatment failure group of sitagliptin for mean 10-month duration

Development of a 13C Stable Isotope Assay for Dipeptidyl Peptidase-4 Enzyme Activity A New Breath Test for Dipeptidyl Peptidase Activity

Dipeptidyl peptidase-4 inhibitors (DPP4i) are a class of orally available, small molecule inhibitors for the management of Type-II diabetes. A rapid, real-time, functional breath test for DPP4 enzyme activity could help to define DPP4i efficacy in patients that are refractory to treatment. We aimed to develop a selective, non-invasive, stable-isotope ¹³C-breath test for DPP4. In vitro experiments were performed using high (Caco-2) and low (HeLa) DPP4 expressing cells. DPP gene expression was determined in cell lines by qRT-PCR. A DPP4 selective ¹³C-tripeptide was added to cells in the presence and absence of the DPP4 inhibitor Sitagliptin. Gas samples were collected from the cell headspace and ¹³CO₂ content quantified by isotope ratio mass spectrometry (IRMS). DPP4 was highly expressed in Caco-2 cells compared to HeLa cells and using the ¹³C-tripeptide, we detected a high ¹³CO₂ signal from Caco2 cells. Addition of Sitaglitpin to Caco2 cells significantly inhibited this ¹³CO₂ signal. ¹³C-assay DPP4 activity correlated positively with the enzyme activity detected using a colorimetric substrate. We have developed a selective, non-invasive, ¹³C-assay for DPP4 that could have broad translational applications in diabetes and gastrointestinal disease.

Characterization of changes in HbA1c in patients with and without secondary failure after metformin treatments by a population pharmacodynamic analysis using mixture models

The objective of the present study was to develop a population pharmacodynamic (PPD) model to describe the glycated hemoglobin (HbA1c)-lowering effects of metformin in type 2 diabetes mellitus patients with and without secondary failure and to characterize changes in HbA1c levels in the two subpopulations using a mixture model. Information on patients was collected retrospectively from electronic medical records. In this study, the mixture model was used to characterize the bimodal effects of metformin. A PPD analysis was performed using NONMEM 7.3.0. A physiological indirect response model, based on 829 HbA1c levels of 69 patients, described the time course for the HbA1c-lowering effects of metformin. Evidence for the different effectiveness of metformin subpopulations was provided using the mixture model. In the final PPD model, the inhibition effect was constant over a study duration in a patient subpopulation without secondary failure. In contrast, the inhibition effect decreased as a function of time after start of metformin treatment in a subpopulation with secondary failure. These results indicated that HbA1c improvements appeared to deteriorate over time in patients with secondary failure. In a PPD analysis of metformin, it was possible to assign patients with secondary failure using the mixture model.

Clinical Characteristics and Metabolic Predictors of Rapid Responders to Dipeptidyl Peptidase-4 Inhibitor as an Add-on Therapy to Sulfonylurea and Metformin

BACKGROUND

Dipeptidyl peptidase-4 (DPP-4) inhibitor add-on therapy is a new option for patients with inadequately controlled type 2 diabetes who are taking combined metformin and sulfonylurea (SU). We evaluated the efficacy and safety of this triple therapy and the characteristics of rapid responders and hypoglycemia-prone patients.

METHODS

We included 807 patients with type 2 diabetes who were prescribed a newly added DPP-4 inhibitor to ongoing metformin and SU in 2009 to 2011. Glycemia and other metabolic parameters at baseline, 12, 24, and 52 weeks, as well as episodes of hypoglycemia were analyzed. Rapid responders were defined as patients with ≥25% reduction in glycosylated hemoglobin (HbA1c) within 12 weeks.

RESULTS

At baseline, while on the submaximal metformin and SU combination, the mean HbA1c level was 8.4%. Twelve weeks after initiation of DPP-4 inhibitor add-on, 269 patients (34.4%) achieved an HbA1c level ≤7%. Sixty-six patients (8.2%, 47 men) were rapid responders. The duration of diabetes was shorter in rapid responders, and their baseline fasting plasma glucose (FPG), HbA1c, C-peptide, and homeostasis model assessment of insulin resistance were significantly higher. Patients who experienced hypoglycemia after taking DPP-4 inhibitor add-on were more likely to be female, to have a lower body weight and lower triglyceride and FPG levels, and to have higher homeostasis model assessment of β-cells.

CONCLUSION

An oral hypoglycemic triple agent combination including a DPP-4 inhibitor was effective in patients with uncontrolled diabetes. Proactive dose reduction of SU should be considered when a DPP-4 inhibitor is added for rapid responders and hypoglycemia-prone patients.

Effects of 6-Month Sitagliptin Treatment on Insulin and Glucagon Responses in Korean Patients with Type 2 Diabetes Mellitus

BACKGROUND

This study aimed to evaluate the effect of sitagliptin, an oral dipeptidyl peptidase-4 inhibitor, on insulin secretion and glucagon suppression in Korean subjects with type 2 diabetes mellitus.

METHODS

Twenty-four subjects underwent a 75-g oral glucose tolerance test (OGTT) before and after 6 months of sitagliptin treatment. Sitagliptin, insulin, and sulfonylurea were withdrawn for 3 days before OGTT to eliminate any acute effects on β-cell insulin or α-cell glucagon secretion. Venous samples were drawn five times during each OGTT to measure plasma glucose, insulin, and glucagon. Indices on insulin secretion and resistance were calculated.

RESULTS

Early phase insulin secretion, measured by the insulinogenic index significantly increased after 6 months of sitagliptin treatment, especially in the higher baseline body mass index group and higher baseline glycosylated hemoglobin (HbA1c) group. There were no significant differences in the insulin resistance indices before and after sitagliptin treatment. Although no significant differences were observed in the absolute levels of glucagon and the glucagon-to-insulin ratio, there was a significant reduction in the percentile change of glucagon-to-insulin ratio at 30- and 120-minute during the OGTT.

CONCLUSION

Although the HbA1c level did not decrease significantly after 6 months of sitagliptin treatment, an increase in insulin secretion and reduction in early phase postprandial plasma glucagon-to-insulin ratio excursion was confirmed in Korean subjects with type 2 diabetes.

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.

One-year real-life efficacy of sitagliptin revealed importance of concomitant pioglitazone use in Japanese patients with type 2 diabetes mellitus

AIMS

Dipeptidyl-peptidase 4 inhibitors have become one of the most popular antidiabetic drugs. However, what kind of combinations with other drugs were advantageous was not known. Here, we tried to elucidate it in a real-life clinical setting.

METHODS

We retrospectively studied efficacies of sitagliptin in 87 Japanese patients with type 2 diabetes mellitus for 52 weeks. We divided subjects into excellent, effective and unresponsive subgroups according to glycemic responses to sitagliptin.

RESULTS

In the excellent and effective groups the minimum HbA1c values were attained at 16 weeks while HbA1c levels in the unresponsive group kept increasing during the study period. There was a significant difference in the baseline HbA1c values between the excellent and unresponsive groups (p=0.02). Interestingly, the mean doses of pioglitazone were highest in the excellent group and lowest in the unresponsive group (p=0.02). When we compared the effective and unresponsive groups, the mean doses of sulfonylureas were constantly higher in the effective group than in the unresponsive group (p=0.05).

CONCLUSIONS

These data suggest that the baseline HbA1c value can be a factor that predicts the extent of HbA1c reduction and reveal a possibility that the concomitant use of pioglitazone augments glycemic responsiveness to sitagliptin.

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.

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

OBJECTIVE

We assessed the predictive parameters for therapeutic efficacy of initial combination therapy with sitagliptin and metformin in drug-naïve type 2 diabetic patients. DeSIGN, PATIENTS, AND MEASUREMENTS: In this 52-week treatment study, 150 patients (mean age, 54·9 ± 12·5 years) with type 2 diabetes and HbA1c of 7·0-10% were treated with sitagliptin 100 mg once and metformin 500 mg twice daily. To assess the predictive parameters for therapeutic efficacy, a multivariate regression analysis was performed with baseline fasting glucose, insulin, C-peptide, and glucagon levels, homoeostasis model assessment-insulin resistance (HOMA-IR) and β-cell function (HOMA-B), insulinogenic index (IGI, defined as 30-0 min insulin/30-0 min glucose), and area under the curve for glucose, insulin, and C-peptide obtained after 75-g oral glucose tolerance test.

RESULTS

After 52 weeks, mean HbA1c levels and fasting and postload 2-h glucose were significantly decreased from 8·7 ± 1·4% to 7·2 ± 1·3%, 9·2 ± 3·0 to 7·2 ± 1·8 mm, and 17·5 ± 5·1 to 10·9 ± 3·6 mm, respectively (P < 0·01). HOMA-B and IGI increased significantly from 50·3 ± 33·5 to 75·1 ± 32·8 and from 11·3 ± 1·3 to 35·0 ± 6·3 at 52 weeks, respectively (P < 0·01). Multivariate regression analysis indicated that the reduction in HbA1c was significantly associated with high baseline HbA1c, low IGI, and short duration of diabetes after adjusting for age, sex, body mass index, blood pressure, triglycerides, creatinine, high-sensitivity CRP, glucagon, C-peptide, HOMA-B, and HOMA-IR. No severe adverse events were observed.

CONCLUSION

These results suggest that drug-naïve type 2 diabetic patients with low β-cell function would benefit the most from early initial combination therapy of sitagliptin and metformin.