Effect of high sucrose diet on insulin secretion and insulin action: a study in the normal rat

Summary The effects of chronic high sucrose feeding for 1 month on in vivo and in vitro insulin secretion and on in vivo insulin action were studied in normal male rats. As compared to the standard chow diet, the high sucrose diet induced excess in vivo insulin response to an intravenous glucose load; the high sucrose diet also slightly improved glucose tolerance, as demonstrated by significantly higher rate of glucose disappearance (p<0.02). The increased insulin secretion in response to glucose in vivo seems to be related to an hyper-reactivity of the pancreatic B cell to glucose, since it was still observed in vitro with the isolated perfused pancreas preparation. By contrast, B cells of sucrose-fed rats exhibited in vitro a normal response to arginine and a significantly lowered (p<0.05) response to acetylcholine. The insulin action in the sucrose-fed rats was quantified in vivo with the insulin-glucose clamp technique. The effects of different concentrations of insulin on glucose production and glucose utilization were studied in anaesthetized rats while in the postabsorptive state. The basal glucose utilization was found significantly higher (p<0.001) in sucrose-fed rats. During the clamp studies the glucose utilization induced by submaximal (400 U/ml) or maximal (7500 U/ml) insulin levels was significantly more important (p<0.02) in the sucrose-fed rats than in the chow-fed rats. This suggests that insulin-mediated glucose uptake is enhanced over a large range of plasma insulin levels in the sucrose-fed rats. In the basal state hepatic glucose production was significantly higher (p<0.001) in sucrose-fed rats. During the clamp studies, the suppression of glucose production induced by submaximal or maximal insulin levels was significantly less effective (p<0.05) in the sucrose-fed rats as compared to chow-fed rats, thus suggesting that the liver becomes resistant to insulin action after sucrose feeding.