Effect of troglitazone, a new oral antidiabetic agent, on fructose-induced insulin resistance.

Troglitazone, a newly developed oral antidiabetic agent, improves hyperglycemia, and has been reported to improve insulin resistance and to decrease hepatic glucose production in diabetic animals. However, the exact mechanism of Troglitazone on the improvement of insulin resistance is not known. Chronic administration of fructose to normal rats leads to hyperglycemia, and hyperinsulinemia; it induces insulin resistance. To reveal the mechanism of Troglitazone, we studied the effect of Troglitazone on serum glucose and insulin in the fructose-induced, insulin-resistant rats. Male Sprague-Dawley (SD) rats were fed either on standard chow or one containing fructose. Troglitazone was administrated as a food admixture (150 mg/kg/day) for 8 weeks. The rats were fed on (1) standard chow, (2) standard chow and Troglitazone, (3) fructose-enriched chow, or (4) fructose-enriched chow and Troglitazone. Blood samples were obtained every two weeks, and the levels of serum glucose and insulin were measured. Fructose-enriched chow increased serum glucose and insulin levels and insulin-to-glucose ratios. Troglitazone improved the fructose-induced increases in serum glucose, insulin levels, and insulin/glucose ratios. In conclusion, Troglitazone improved the fructose-induced insulin resistance.