Effects of a protein preload on gastric emptying, glycemia, and gut hormones after a carbohydrate meal in diet-controlled type 2 diabetes

Abstract

Objective: We evaluated whether a whey preload could slow gastric emptying, stimulate incretin hormones, and attenuate postprandial glycemia in type 2 diabetes.

Research design and methods: Eight type 2 diabetic patients ingested 350 ml beef soup 30 min before a potato meal; 55 g whey was added to either the soup (whey preload) or potato (whey in meal) or no whey was given.

Results: Gastric emptying was slowest after the whey preload (P < 0.0005). The incremental area under the blood glucose curve was less after the whey preload and whey in meal than after no whey (P < 0.005). Plasma glucose-dependent insulinotropic polypeptide, insulin, and cholecystokinin concentrations were higher on both whey days than after no whey, whereas glucagon-like peptide 1 was greatest after the whey preload (P < 0.05).

Conclusions: Whey protein consumed before a carbohydrate meal can stimulate insulin and incretin hormone secretion and slow gastric emptying, leading to marked reduction in postprandial glycemia in type 2 diabetes.

Figure 1

Gastric emptying (A), concentrations of blood glucose (B), plasma insulin (C), plasma GLP-1 (D), plasma GIP (E), and plasma CCK (F) in response to a mashed potato meal in eight type 2 diabetic patients. On each study day, subjects ingested 350 ml beef-flavored soup 30 min before a radiolabeled mashed potato meal; 55 g whey protein was added either to the soup (whey preload) or to the potato (whey in meal) or no whey was given (no whey). Data are means ± SE. *P < 0.05, whey preload vs. whey in meal; #P < 0.05, whey in meal vs. no whey; §P < 0.05, whey preload vs. no whey.