Sakura H, et al. - Here, physicians assessed the differences in the therapeutic effect, and efficacy, of sitagliptin in patients with type 2 diabetes mellitus (T2DM) based on the month administration of the drug, began as sub-analysis of the JAMP Study. Despite excluding the influence of hemoglobin A1c (HbA1c) value from the analysis at the start of treatment, the season of administration of sitagliptin affected the subsequent hypoglycemic effect.Findings provided a possibility that seasonal fluctuations had an effect on the efficacy of antidiabetic drugs.