Indices of insulin sensitivity and secretion from a standard liquid meal test in subjects with type 2 diabetes, impaired or normal fasting glucose

Abstract

Background. To provide an initial evaluation of insulin sensitivity and secretion indices derived from a standard liquid meal tolerance test protocol in subjects with normal (NFG), impaired fasting glucose (IFG) or type 2 diabetes mellitus. Methods. Areas under the curve (AUC) for glucose, insulin and C-peptide from pre-meal to 120 min after consumption of a liquid meal were calculated, as were homeostasis model assessments of insulin resistance (HOMA2-IR) and the Matsuda index of insulin sensitivity. Results. Subjects with NFG (n = 19), IFG (n = 19), and diabetes (n = 35) had mean SEM HOMA2-IR values of 1.0 0.1, 1.6 0.2 and 2.5 0.3 and Matsuda insulin sensitivity index values of 15.6 2.0, 8.8 1.2 and 6.0 0.6, respectively. The log-transformed values for these variables were highly correlated overall and within each fasting glucose category (r = -0.91 to -0.94, all p < 0.001). Values for the product of the insulin/glucose AUC ratio and the Matsuda index, an indicator of the ability of the pancreas to match insulin secretion to the degree of insulin resistance, were 995.6 80.7 (NFG), 684.0 57.3 (IFG) and 188.3 16.1 (diabetes) and discriminated significantly between fasting glucose categories (p < 0.001 for each comparison). Conclusion. These results provide initial evidence to support the usefulness of a standard liquid meal tolerance test for evaluation of insulin secretion and sensitivity in clinical and population studies. © 2009 Maki et al.; licensee BioMed Central Ltd.