Urinary chiro-Inositol Excretion is an Index Marker of Insulin Sensitivity in Japanese Type II Diabetes

OBJECTIVE To determine the relationship between urinary chiro-inositol excretion and insulin sensitivity in Japanese type II diabetic patients. RESEARCH DESIGN AND METHODS Eighteen subjects were age-matched, nonobese, type II diabetic patients. Eight subjects had impaired glucose tolerance (IGT), and 10 had normal glucose tolerance (NGT). We quantified urinary chiro-inositol excretion using gas chromatography-mass spectrometry and the insulin sensitivity index (SI), and glucose effectiveness (SG) using Bergman's modified minimal model method. RESULTS The urinary excretion of chiro-inositol was much lower in the diabetic patients (32.3 ± 16.0 μmol/day, means ± SD) than in the NGT subjects (96.0 ± 17.6; P < 0.0001) and IGT subjects (58.9 ± 11.6; P < 0.0001). SI was much lower in the diabetic patients (3.81 ± 1.49) than in the NGT subjects 6.30 ± 1.59, P < 0.0005). SG was much lower in the diabetic patients (2.14 ± 0.56) than in the NGT subjects (3.07 ± 0.38, P < 0.0001). There was a significant correlation between urinary chiro-inositol excretion and SI (r = 0.766), as well as a significant correlation between urinary chiro-inositol excretion and SG (r = 0.747). CONCLUSIONS There is a direct relationship of urinary chiro-inositol excretion to insulin sensitivity and SG in humans. Urinary chiro-inositol excretion might be useful as a metabolic index of insulin sensitivity in type II diabetes.