Obesity may attenuate the HbA1c-lowering effect of sitagliptin in Japanese type 2 diabetic patients.

Aims/Introduction: The aim of the present study was to assess the independent predictors of the HbA1c-lowering effect of sitagliptin in Japanese type 2 diabetic patients. Materials and Methods: Data were retrieved from the medical records of 151 type 2 diabetic patients who had been taking sitagliptin 25 or 50 mg once daily for inadequate glycemic control for at least 12 weeks, with or without other oral hypoglycemic agents. Spearman's rank correlation coefficients were calculated to investigate correlations between two independent continuous variables. Multiple stepwise regression analysis was used to identify independent predictors of reductions in HbA1c levels after 12 weeks of sitagliptin treatment (DHbA1c). Results: In all patients combined, Spearman's rank correlation coefficients showed that Delta HbA1c was significantly correlated with baseline HbA1c alone (r = 0.371, P < 0.0001). However, multiple linear regression analysis among all patients using baseline variables revealed that the independent factors contributing to DHbA1c, in order of importance, were method of prescribing (P < 0.0001), baseline HbA1c (P < 0.0001), body mass index (BMI; P = 0.004), and duration of diabetes (P = 0.024). Conclusions: Our analysis may provide novel evidence that increased BMI contributes, in part, to attenuation of the HbA1c-lowering effect of sitagliptin in Japanese type 2 diabetic patients. Analysis of a larger population over a longer period of time is warranted to confirm these findings. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00156.x, 2012)