Insulin resistance in adipose tissue increases the release of
free fatty acids into the circulation, which likely contributes to impaired
insulin action in liver and skeletal muscle associated with
obesity. However, reliable assessment of adipose tissue
insulin resistance requires performing a hyperinsulinemic-euglycemic clamp procedure in conjunction with a
fatty acid tracer infusion to determine
insulin-mediated suppression of lipolytic rate. We developed a simpler method for evaluating adipose tissue
insulin resistance in vivo, determined as the product of
palmitate rate of appearance into the bloodstream and plasma
insulin concentration during basal conditions. We validated our Adipose Tissue
Insulin Resistance Index (ATIRI) by comparison with an assessment of adipose tissue
insulin resistance determined by using the hyperinsulinemic-euglycemic clamp procedure in conjunction with a
palmitate tracer infusion in 47 obese nondiabetic subjects (body mass index: 40.1 ± 9.3 kg/m(2)). We found the ATIRI correlated closely with adipose tissue
insulin resistance assessed during the clamp procedure (r =-0.854, P < 0.001). These results demonstrate that the ATIRI provides a reliable index of adipose tissue
insulin resistance in obese subjects.