Effects of a Carbohydrate-, Glutamine-, and Antioxidant-Enriched Oral Nutrition Supplement on Major Surgery-Induced Insulin Resistance: A Randomized Pilot Study

Abstract

Background: Insulin resistance after surgery hampers recovery. Oxidative stress is shown to be involved in the occurrence of postoperative insulin resistance. Preoperative carbohydrate-rich oral nutrition supplements reduce but do not prevent insulin resistance. The aim of the present study was to investigate the effect of a carbohydrate-, glutamine-, and antioxidant-enriched preoperative oral nutrition supplement on postoperative insulin resistance.

Methods: A double-blind randomized controlled pilot study in 18 patients with rectal cancer, who received either the supplement (S) or the placebo (P) 15, 11, and 4 hours preoperatively, was conducted. Insulin sensitivity was studied prior to surgery and on the first postoperative day using a hyperinsulinemic euglycemic 2-step clamp.

Results: Hepatic insulin sensitivity (insulin-mediated suppression of glucose production) decreased significantly after surgery in both groups, with no differences between the groups. Peripheral insulin sensitivity (glucose rate of disappearance, Rd) was significantly decreased after surgery in both groups (S: 37.2 [19.1-50.9] vs 20.6 [13.9-27.9]; P: 23.8 [15.7-35.5] vs 15.3 [12.6-19.1] µmol/kg·min) but less pronounced in the supplemented group (P = .04). The percentage decrease in glucose Rd did not differ between the groups. Adipose tissue insulin sensitivity (insulin-mediated suppression of plasma free fatty acids) decreased to the same extent after surgery in both groups.

Conclusion: Rectal cancer surgery induced profound insulin resistance, affecting glucose and fatty acid metabolism. The preoperative nutrition supplement somewhat attenuated but did not prevent postoperative peripheral insulin resistance.

Keywords: antioxidants; glutamine; rectal cancer; surgery-induced insulin resistance.