Traditional blood glucose lowering agents do not prevent the progressive loss of beta cell function in patients with type 2 diabetes. The dipeptidylpeptidase (DPP)-4 inhibitor vildagliptin improves beta cell function both acutely and chronically (up to 2 years). Whether this effect persists after cessation of treatment remains unknown. Here, we assessed the insulin secretory capacity in drug-naive patients with type 2 diabetes after a 52 week treatment period with vildagliptin or placebo, and again after a 12 week washout period.