Blood glucose, insulin and proinsulin levels after a test meal. T2DM patients treated with metformin and sulfonylurea (S+M), insulin glargine (G+M) or a DPP-4 inhibitor (D+M) as well as non-diabetic controls (C) received a standardized test meal. Over the course of 5 h, (a) blood glucose, (b) insulin, and (c) proinsulin levels were determined at intervals of 30 min. Each group consisted of 20 individuals on average. All three serum parameters increased after the test meal reaching their peak between 60 and 90 min after the test meal. “ p < 0.05, * p < 0.01 and ° p < 0.001 as compared to C.