Insulin and glucose responses in rats fed sucrose or starch

Rats fed 54% sucrose for 11 to 13 weeks ad libitum or 5 weeks ad libitum followed by 6 to 8 weeks of meal feeding had significantly higher serum insulin, glucose, and triglyceride levels than rats fed comparable amounts of starch after 12 to 14 hr without food. The serum insulin response measured before, 1/2, and 4 hr after a meal showed insulin levels of sucrose-fed rats to be higher than comparable levels of rats fed starch at all three times. An intraperitoneal glucose tolerance test measuring serum glucose before, 1/2, 2, and 2 hr after a glucose injection revealed glucose levels of rats fed sucrose to be higher than levels of rats fed starch. When insulin was added to the injection medium, serum glucose of rats fed sucrose remained higher than comparable levels of rats fed starch indicating insulin insensitivity. Meal feeding generally resulted in higher insulin and triglyceride levels than in rats fed ad libitum but had little effect on glucose levels. These results are clear evidence that sucrose feeding has undesirable effects on glucose tolerance.