Effects of Dietary Fructose on Plasma Glucose and Hormone Responses in Normal and Hyperinsulinemic Men

Twelve men with abnormally high insulin responses to a sucrose load and 12 normal men were fed diets containing 0, 7.5, or 15% of the calories as fructose for 5 weeks each. The diets contained approximately 43% of the calories as total carbohydrate, 42% as fat and 15% as protein. Mean insulin responses of the hyperinsulinemic men were initially 235% of control responses. Plasma glucose concentrations 1 hour after the sucrose load were significantly higher in hyperinsulinemic men than in controls. There were no initial differences between the two groups in glucagon or gastric inhibitory polypeptide (GIP) responses. Consumption of 7.5 and 15% Fructose diets increased fasting plasma glucose and GIP responses in both groups. Consumption of the 15% fructose diet resulted in significantly higher insulin and glucose responses than consumption of the other two diets. These results indicate that moderate levels of dietary fructose can produce undesirable changes in glucose metabolism of both normal and hyperinsulinemic men.