Determination of urinary myo-inositol concentration by an improved enzymatic cycling method using myo-inositol dehydrogenase from Flavobacterium sp.

Abstract Background : To determine myo -inositol more accurately, we improved the enzymatic cycling method. Methods : We screened myo -inositol dehydrogenase (MIDH; EC.1.1.1.18) from Flavobacterium sp., which was highly specific to myo -inositol. We measured urinary myo -inositol/creatinine ratio 2 h after 75-g oral glucose tolerance test (2 h MI) of 71 volunteers, and investigated the relationship between diabetes and urinary myo -inositol concentration. Results : The calibration curve was linear ( r =1.00) up to 2000 μmol/l, and the detection limit was 10 μmol/l. Within-run and between-run CVs were 0.5–1.1% and 0.4–1.3%, respectively. The 2 h MI of impaired fasting glycemia (IFG; 65.1±46.6 mg/g Cr, P P P Conclusions : The myo -inositol measurement method demonstrated high specificity and yielded accurate results. The results of clinical trials suggested that 2 h MI could not only determine diabetes but also distinguish IFG and IGT from NGT.