Factors associated with the glucose-lowering effect of vildagliptin identified from the results of the oral glucose tolerance test in Japanese patients with type 2 diabetes

Abstract

In order to investigate the factors contributing to the glucose-lowering effect of vildagliptin, we analyzed the results of the oral glucose tolerance test together with several clinical parameters in Japanese patients with type 2 diabetes before and after 24 weeks of treatment with vildagliptin. The data of the 13 patients who satisfactorily completed the follow-up examinations were included. After 24 weeks treatment with vildagliptin, the patients were classified into a responder group (69.2%) and a non-responder group (30.8%); the responders consisting of subjects whose HbA1c decreased following 24 weeks treatment with vildagliptin, and the non-responders consisting of subjects who did not show any significant decrease of HbA1c. There were no differences in baseline characteristics between the two groups before administration of vildagliptin. After 24 weeks of treatment, HbA1c was significantly reduced from 7.3 ± 0.5% to 6.7 ± 0.5% in the responder group (P = 0.0077), while it tended to rather increased from 7.1 ± 0.6% to 7.5 ± 0.7% in the nonresponder group (P = 0.0679). Also, parameters reflecting the glucose-stimulated insulin secretion, such as the insulinogenic index and oral disposition index, were significantly higher in the responder group than in the non-responder group, whereas insulin sensitivity was similar between the two groups. These results suggest that the difference in the degree of improvement of the glucose tolerance between the responder group and non-responder group in this study could be associated with the effect of vildagliptin on the glucose-stimulated insulin secretion, but not on the insulin sensitivity. © The Japan Endocrine Society.