Comparison of the [13C]Glucose Breath Test to the Hyperinsulinemic-Euglycemic Clamp When Determining Insulin Resistance

Comparison of the [ 13 C]Glucose Breath Test to the Hyperinsulinemic-Euglycemic Clamp When Determining Insulin Resistance Richard Z. Lewanczuk , MD, PHD , Breay W. Paty , MD and Ellen L. Toth , MD From the Division of Endocrinology, University of Alberta, Edmonton, Canada Address correspondence and reprint requests to Dr. Richard Lewanczuk, Division of Endocrinology, 362 HMRC, University of Alberta, Edmonton, Alberta, Canada T6G 2S2. E-mail: rlewancz{at}gpu.srv.ualberta.ca Abstract 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 C]glucose, 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 C]glucose breath test and the hyperinsulinemic-euglycemic clamp. Results from the [ 13 C]glucose 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 C]glucose 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 C]glucose breath test may provide a useful noninvasive assessment of insulin sensitivity. ADA, American Diabetes Association HOMA, homeostasis model assessment ISI, insulin sensitivity index QUICKI, quantitative insulin sensitivity check index Footnotes R.Z.L. holds stock in Isotechnika Inc. A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. Accepted October 21, 2003. Received August 5, 2003. DIABETES CARE