Glucose tolerance and serum insulin levels in an animal model of obesity induced by sub-acute or chronic administration of antipsychotic drugs.

1. To assess the role of insulin in the development of the obesity induced by antipsychotic drugs, a glucose tolerance test was conducted in female rats after 0 or 30 days of sulpiride administration. 2. At day 10, the area under the glucose curve did not differ between sulpiride and vehicle-treated rats, however, the area under the insulin curve was significantly decreased by sulpiride. At day, 30 the insulin response was similar in both groups, but the area under the glucose curve was significantly lower in the sulpiride-treated rats. 3. The results suggest that insulin resistance and hyperinsulinemia are not involved in the development and maintenance of the obesity induced by sulpiride. Contrarily, these findings may be related to an increased insulin sensitivity. 4. The absence of hyperinsulinemia and insulin resistance indicates important differences between primary obesity in humans and rodents and this model of drug-induced excessive weight gain.