A study of urinary myo-inositol as a sensitive marker of glucose intolerance

Abstract

Background: We assessed the possibility of using myo-inositol as a marker of glucose intolerance. Methods: We measured urinary myo-inositol enzymatically before and 2 h after a 75-g oral glucose tolerance test in 564 volunteers, who were divided into four groups [normal glucose tolerance (NGT), impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and diabetes mellitus (DM)]. Furthermore, we classified NGT into NGT-A (2-h blood glucose <120 mg/dl and 2-h glucosuria <50 mg/dl) and NGT-B (remaining NGT subjects). We then compared Δ myo-inositol ( myo-inositol/creatinine ratio: 2-h after glucose load—before load) of each group to investigate the relationship between glucose intolerance and Δ myo-inositol. Results: The glucose tolerance of NGT-B appeared to have deteriorated compared with NGT-A as determined by blood glucose, insulin, and glucosuria. There was very little effect of gender or age on Δ myo-inositol in NGT-A. Δ myo-inositol was significantly higher than that in NGT-A (0.5±7.1 mg/g Cr) not only in IFG (8.7±19.5 mg/g Cr, P<0.0001), IGT (14.8±22.9 mg/g Cr, P<0.0001) and DM (79.5±37.1 mg/g Cr, P<0.0001), but in NGT-B (7.4±12.7 mg/g Cr, P<0.0001). With 2 mg/g Cr as a tentative cut-off for Δ myo-inositol to detect NGT-A, sensitivity and specificity were 68% and 72%, respectively. Conclusions: The Δ myo-inositol can be use of a non-invasive and sensitive marker for glucose intolerance.