Differential effects of high-carbohydrate and high-fat diet composition on muscle insulin resistance in rats.

This study was conducted to evaluate whether the composition of carbohydrate or fat diet affects insulin resistance by measuring the muscle glucose transport rate. Both high-sucrose and high-starch diet with or without high-fat decreased insulin-stimulated glucose transport, but there were no significant differences among groups. Calorie intake in both high-sucrose and high-starch diet groups was higher than in chow group. The high-fat high-sucrose diet induced decrease in insulin-stimulated glucose transport was partially improved by supplement with fish oil. Calorie intake in high-fat high-sucrose and fish oil supplemented groups was higher than in chow group. The decreased insulin-stimulated glucose transport was accompanied by the increase in visceral fat mass, plasma triglyceride and insulin levels. These changes were improved by the supplement with fish oil. These results demonstrate that the composition of fat in diet is clearly instrumental in the induction of muscle insulin resistance. However, in high carbohydrate diet, it is likely that the amount of calorie intake may be a more important factor in causing insulin resistance than the composition of carbohydrate. Thus, the compositions of carbohydrate and fat in diet differentially affect on muscle insulin resistance.