Comparison of the 13CGlucose Breath Test to the Hyperinsulinemic-Euglycemic Clamp When Determining Insulin Resistance

OBJECTIVE: With increasing emphasis on the recognition of the metabolic syndrome and early type 2 diabetes, a clinically useful measure of insulin resistance is desirable. The purpose of this study was to evaluate whether an index of glucose metabolism, as measured by (13)CO(2) generation from ingested (13)Cglucose, would correlate with indexes from the hyperinsulinemic-euglycemic clamp. RESEARCH DESIGN AND METHODS: A total of 26 subjects with varying degrees of insulin sensitivity underwent both the (13)Cglucose breath test and the hyperinsulinemic-euglycemic clamp. Results from the (13)Cglucose breath test were compared with measures of insulin sensitivity from the glucose clamp as well as with other commonly used indexes of insulin sensitivity. RESULTS: There was a strong correlation between the (13)Cglucose breath test result and the glucose disposal rate (r = 0.69, P < 0.0001) and insulin sensitivity index (r = 0.69, P < 0.0001) from the insulin clamp. The magnitude of these correlations compared favorably with QUICKI and were superior to the homeostasis model assessment. CONCLUSIONS: The (13)Cglucose breath test may provide a useful noninvasive assessment of insulin sensitivity.