The BIGTT Test: A novel test for simultaneous measurement of pancreatic [beta]-cell function, insulin sensitivity, and glucose tolerance

• Published in: Diabetes care Vol. 30; no. 2; p. 257
• Main Authors: Hansen, Torben, Drivsholm, Thomas, Urhammer, Søren A, Palacios, Rene T
• Format: Journal Article
• Language: English
• Published: Alexandria American Diabetes Association 01.02.2007
• Subjects: Diabetes; Diet; Informed consent; Insulin; Medical research; Statistical methods; Studies
• ISSN: 0149-5992
• DOI: 10.2337/dc06-1240

Insulin resistance and impaired β-cell function are key elements in the pathogenesis of type 2 diabetes. We aimed to develop valid algorithms for estimation of the insulin sensitivity index (S^sub I^) and acute insulin response (AIR) derived from simple and cheap physiological measurements that could be used in large-scale metabolic, genetic, and epidemiological studies. For our purpose, data from an oral glucose tolerance test (OGTT) (18 samples during 240 min) and a tolbutamide-modified intravenous glucose tolerance test (IVGTT) (33 samples during 180 min) from 258 individuals with fasting plasma glucose <7 mmol/l and 2-h plasma glucose <7.8 mmol/l were used for model development and internal validation. Data from an additional 28 individuals were used for external validation. Bergman's minimal model was used to calculate S^sub I^, and the trapezoidal method was used to calculate AIR^sub 0-8 min^. Multiple linear regression was applied to derive predictive equations of log(S^sub I^) and log(AIR^sub 0-8 min^) using data on sex, BMI, plasma glucose, and serum insulin levels obtained during the OGTT. We demonstrate that it is possible to obtain estimates of S^sub I^ (BIGTT-S^sub I^) and AIR (BIGTT-AIR) that are highly correlated to IVGTT-derived values of S^sub I^ (R^sup 2^ = 0.77) and AIR (R^sup 2^ = 0.54). In the two validation datasets we obtained similar results. Data from OGTTs can provide accurate measures of insulin sensitivity and β-cell function, which can be used in large scale metabolic, genetic, and epidemiological studies.