Low Dose Fat-Induced Insulin Resistance

This study is designed to test the hypothesis that a low-dose of fatty acid infusion (Intralipid/heparin) will cause mild insulin resistance. This dose-finding study is critical for future studies on free-fatty acid induced insulin resistance. Healthy male and healthy female volunteers will undergo a 6 hour hyperinsulinemic-euglycemic clamp, in order to establish insulin sensitivity parameters in the presence of fatty acid co-infusion. The subjects will then return 1-3 weeks later, and undergo another 6 hour HIE clamp, this time in the presence of low-dose fatty acid co-infusion (30ml/hr). If this dose does not achieve \~25% reduction in the rate of glucose disposal, then the dose-confirmation study will be repeated 1-3 weeks later with a medium-dose fatty acid co-infusion (60ml/hr). A dose-response effect of fatty acids on insulin resistance has been demonstrated before, but not in the precise conditions of our study. This dose-finding study is critical because future studies require a reliable dose of fatty acid infusion, and the exact dose of fatty acid infusion that causes mild insulin resistance may be different in the conditions of our study.