Effects of Diet on Bile Acid Metabolism and Insulin Resistance in Type 2 Diabetic Rats after Roux-en-Y Gastric Bypass

Background Roux-en-Y gastric bypass (RYGB) is effective for the treatment of type 2 diabetes mellitus; however, the mechanism remains unclear. Methods The effects of RYGB on postprandial responses to three different diets (low carbohydrate (CH)-rich diet, high CH-rich diet, and fat-rich diet) of different nutritional composition in a Goto-Kakizaki (GK) diabetic rat model were assessed by measuring glucose tolerance, insulin resistance, incretin responses, and bile acid (BA) metabolism. Results GK-RYGB group rats lost weight and preferred low CH-rich diet, but there were no significant differences in BW among the different diets. Glucose tolerance and insulin resistance were improved in rats who underwent RYGB, together with higher levels of circulating BAs, plasma GLP-1, and PYY levels. GK-RYGB rats fed high CH-rich or fat-rich diet showed increased glucose level and insulin resistance, together with high plasma BA, GIP, and PYY levels compared to those fed a low CH-rich diet. Conclusion RYGB improves glucose tolerance and insulin resistance which may be related to BA metabolism and hormone levels, and the nutrient composition of the diet affects the treatment effect of RYGB on T2DM.