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 β 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 β 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 β 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. β cell function was evaluated by HOMA-β 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-β and HOMA-IR were improved (P<0.01) after two weeks’ treatment with insulin, while HOMA-β 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 β cell function in newly diagnosed Chinese type 2 diabetes, and the improvements in β cell function was preserved after 3 months of sitagliptin.