Effects of Sitagliptin on Pancreatic beta Cell Function and Microangiopathy in Japanese Patients With Type 2 Diabetes Mellitus: Follow-Up for 4 Years

Background: This study was aimed at investigating the effect of long-term sitagliptin treatment in improving the pancreatic beta cell function and its influence on microangiopathy in patients with type 2 diabetes mellitus. Methods: The study was designed as a retrospective analysis of the data of 27 patients with type 2 diabetes mellitus who did not have any evident reduction of the renal function and had received sitagliptin treatment for 4 years or longer. The fasting plasma C-peptide level corrected for the fasting blood glucose level (C-peptide index (CPI)), hemoglobin A1c (HbA1c) and body weight were determined every year during the 4-year period, and the status of retinopathy and nephropathy at the end of the fourth year of sitagliptin treatment was compared with the pre-treatment status. Results: Both the HbA1c and body weight were significantly decreased by 6 months after the start of treatment. Thereafter, the HbA1c showed no further rise during the subsequent 4-year period, while the body weight continued to decrease over the 4-year period. No significant change of the CPI, as compared to the pre-treatment level (0.95 +/- 0.49), was observed at any time during the follow-up. The retinopathy and nephropathy remained unchanged in severity in most cases; however, progression of retinopathy was seen in seven cases (29%) and that of nephropathy in three cases (11%). Conclusions: Maintenance of good blood glucose control for 4 years by sitagliptin treatment allowed the pancreatic beta cell function to be preserved. However, it was not possible to suppress progression of microangiopathy completely by treatment for a short period of 4 years.