The effects of added whey protein to a pre-operative carbohydrate drink on glucose and insulin response

Pre-operative complex carbohydrate (CHO) drinks are recommended to attenuate post-operative insulin resistance. However, many institutions use simple CHO drinks, which while convenient, may have less metabolic effects. Whey protein may enhance insulin release when added to complex CHO. The aim of this study was to compare the insulin response to simple CHO vs. simple CHO supplemented with whey protein.

Twelve healthy volunteers participated in this double-blinded, within subject, cross-over design study investigating insulin response to simple CHO drink vs. simple CHO + whey (CHO + W) drink. The primary outcome was the accumulated insulin response during 180 min after ingestion of the drinks (Area under the curve, AUC). Secondary outcomes included plasma glucose and ghrelin levels, and gastric emptying rate estimated by acetaminophen absorption technique. Data presented as mean (SD).

There was no differences in accumulated insulin response after the CHO or CHO + W drinks [AUC: 15 (8) vs. 20 (14) nmol/l, P = 0.27]. Insulin and glucose levels peaked between 30 and 60 min and reached 215 (95) pmol/l and 7 (1) mmol/l after the CHO drink and to 264 (232) pmol/l and 6.5 (1) mmol/l after the CHO + W drink. There were no differences in glucose or ghrelin levels or gastric emptying with the addition of whey.

The addition of whey protein to a simple CHO drink did not change the insulin response in healthy individuals. The peak insulin responses to simple CHO with or without whey protein were lower than that previously reported with complex CHO drinks. The impact of simple carbohydrate drinks with lower insulin response on peri-operative insulin sensitivity requires further study.