Simple and non-invasive screening method for diabetes based on myoinositol levels in urine samples collected at home

Objective To establish a simple screening method for diabetes based on myoinositol (MI) in urine samples collected at home. Research design and methods Initially, we evaluated the stability of urinary MI (UMI) at room temperature (RT; 25°C) and 37°C in 10 outpatients with type 2 diabetes. We then enrolled 115 volunteers without a current or history of diabetes. In all subjects, glucose intolerance was diagnosed by 75 g oral glucose tolerance test (75gOGTT). To assess the association between UMI or urine glucose (UG) and plasma glucose (PG), urine samples were also collected at 0 and 2 hours during 75gOGTT. All the subjects collected urine samples at home before and 2 hours after consuming the commercially available test meal. UMI levels at wake-up time (UMIwake-up), before (UMIpremeal) and 2 hours after the test meal (UMI2h-postprandial) were measured using an enzymatic method. ΔUMI was defined as UMI2h-postprandial minus UMIpremeal. Results Differing from UG, UMI was stable at RT and 37°C. UMI was increased linearly along with an increase in PG, and no threshold for UMI was observed. UMI was closely associated with blood glucose parameters obtained from a 75gOGTT and hemoglobin A1c (HbA1c) at hospital after adjustment for age, sex, body mass index and serum creatinine. UMIwake-up, UMIpremeal, UMI2h-postprandial and ΔUMI at home were higher in diabetic subjects than non-diabetic subjects even after the above adjustment. Receiver operating characteristics curve (ROC) analyses revealed that for the screening of diabetes, the area under the curve for ROC for UMI2h-postprandial and ΔUMI (0.83 and 0.82, respectively) were not inferior to that for HbA1c ≥48 mmol/mol, which is the American Diabetes Association (ADA) criteria for diabetes. Conclusions MI measurement in urine samples collected at home before and after the meal would be a simple, non-invasive and valuable screening method for diabetes.