CHANGES IN INSULIN ACTION, TRIGLYCERIDES, AND LIPID-COMPOSITION DURING SUCROSE FEEDING IN RATS

In the present study, the time course of change in sucrose-induced ins ulin resistance, triglyceride (TG) concentration, and liver fatty acid composition was examined. Male rats (n = 8-10/group per time point) w as fed a high-starch (ST) diet for 2 wk and were then equicalorically fed ST or a high-sucrose (SU) diet for 1, 2, 5, or 8 wk. Body weight a nd percent body fat were similar between ST and SU diets at all time p oints. Glucose infusion rate (GIR) was significantly (P < 0.05) lower in the SU diet (9.2 +/- 0.9, 7.4 +/- 0.5, 6.2 +/- 1.0, and 6.0 +/- 0.9 mg . kg(-1). min(-1)) vs. the ST diet(15.1 +/- 1.7, 15.7 +/- 0.7, 14. 7 +/- 0.9, and 14.2 +/- 0.9 mg kg(-1). min(-1)) at 1, 2, 5, and 8 wk, respectively. Reduced suppression of glucose appearance accounted for 85, 50, 45, and 40% of the reduction in GIR at these same time points. Muscle glycogen synthesis was reduced (P < 0.05 vs. ST diet) in the S U diet at 2, 5, and 8 wk. Fasting plasma TG concentration was inversel y related (r = -0.79, P < 0.001) to muscle glycogen synthesis, and liv er TG concentration was positively related (r = 0.59, P < 0.01) to glu cose appearance. Liver fatty acid composition was similar between diet groups. In summary, the SU diet produced insulin resistance in liver before muscle. TG concentration appears to be related to sucrose-induc ed insulin resistance in liver and muscle.