INS and type 2 diabetes mellitus: In contrast, in people with type 2 diabetes, insulin secretory responses show the typical slow rise to a peak, occurring later than in healthy individuals, after oral glucose ingestion, but this response is only marginally higher than that to ‘isoglycaemic’ i.v. glucose (Fig. 1b,e,h,l), indicating a substantially reduced or, in some individuals, absent incretin effect [2–4].