Abstract
Objective: To assess the possibility of using regulated meal load for myoinositol measurement instead of glucose loading.
Methods: Subjects were 47 volunteers who underwent 75-g oral glucose tolerance testing (OGTT) and were classified according to 1998 WHO criteria. For subjects with normal glucose tolerance, those with 1 h plasma glucose ≥180 mg/dl were defined as pre-borderline. On a separate day, the subjects also underwent a regulated meal load test (MT). We measured urinary myoinositol before and 2 h after both OGTT and MT and then change in urinary myoinositol (ΔUMI: myoinositol/creatinine ratio 2 h after loading-myoinositol/creatinine ratio before loading) was compared between the 2 tests. In addition, we investigated the relationship between glucose intolerance and ΔUMI.
Results: A good correlation was seen between ΔUMI for OGTT and that for MT (r=0.853). Lower glucose tolerance was associated with a greater ΔUMI. Setting 6 mg/gCr as a tentative cut-off value for MT to detect glucose intolerance, ΔUMI was positive in 93.3% of patients (14/15) with diabetes mellitus (DM) and 100% (6/6) with impaired glucose tolerance (IGT). Conversely, for OGTT, ΔUMI was positive in 100% of subjects with DM (15/15) and 66.7% of those with IGT (4/6). Thus the positive rate for ΔUMI of MT was quite similar to that of OGTT.
Conclusion: These results show that ΔUMI from the MT can be used as a non-invasive and sensitive marker of glucose intolerance since it is comparable to that from the OGTT.
