Effect of Initial Intensive Insulin Therapy Followed by Sitagliptin on ? Cell Function in Patients with New Onset Type 2 Diabetes

Objective: It is established that early insulin therapy can improve both beta cell function and glycaemic control in newly diagnosed type 2 diabetic patients. The dipeptidyl peptidase-4 (DPP-4) inhibitor, sitagliptin, can preserve or even increase the number of beta cells in animal models of diabetes. Therefore, we aimed to determine whether treatment with sitagliptin after initial intensive insulin therapy would further reduce glycaemia and preserve beta cell function in new-onset type 2 diabetes. Methods: 48 Chinese patients with newly diagnosed type 2 diabetes (fasting blood glucose concentration 13.42 +/- 0.38 mmol/L; HbA1c:11.8 +/- 0.2%) were recruited. All received insulin pump therapy for two weeks, followed by sitagliptin (100mg orally once daily) for three months. Arginine tests were performed at baseline, after two-weeks' insulin pump therapy, and after 3 months' sitagliptin therapy. Blood samples were collected at baseline, before and after the treatment with sitagliptin for measurement of blood glucose, plasma insulin and lipids profiles. beta cell function was evaluated by HOMA-beta and the insulin response to arginine. Results: Fasting blood glucose concentrations were substantially decreased after two weeks' insulin therapy (P<0.01), and were further reduced after 3 months' treatment with sitagliptin (P<0.01). HOMA-beta and HOMA-IR were improved (P<0.01) after two weeks' treatment with insulin, while HOMA-beta was further improved after 3 months' sitagliptin (P<0.01). However, the insulin response to arginine did not increase after two weeks' insulin therapy, but did improve after sitagliptin (P<0.05). Conclusions: Intensive insulin therapy improved both glycaemic control and beta cell function in newly diagnosed Chinese type 2 diabetes, and the improvements in beta cell function was preserved after 3 months of sitagliptin.