Glycohemoglobin not as predictive as fasting glucose as a measure of prediabetes in predicting proteinuria

BackgroundThere is little data on the assessment of prediabetes with proteinuria.MethodsThis is a cross-sectional cohort study assessing prediabetes with proteinuria in a large Japanese population. Using a nationwide health checkup database of 228 778 Japanese aged <20 years (median 66 years; 39.3 were men; none had pre-existing cardiovascular disease), we examined the association between prediabetes and proteinuria (<1 on dipstick) separately in prediabetes subjects diagnosed with the new hemoglobin A1c (HbA1c) criterion only (PD-A1c), the impaired fasting plasma glucose only (PD-IFG) and fulfilling both criteria (PD-Both).ResultsAccording to the American Diabetes Association's (ADA's) criterion of 5.7-6.4 HbA1c and/or 100-125 mg/dL fasting plasma glucose, 43.8 of the subjects were judged as having prediabetes. Prediabetes subjects were divided into subclasses of PD-A1c (53.7), PD-IFG (21.7) and PD-Both (24.5), respectively. Therefore, 21.7 of prediabetes subjects were missed using the new HbA1c criterion only. Compared with subjects with normal glucose tolerance (as a reference), the odds ratio (OR) [95 confidence interval (95 CI)] for the increased risk of proteinuria (<1) in diabetes itself was 2.191 (2.081-2.307) and in whole prediabetes was 1.093 (1.046-1.142); when prediabetes was subdivided, the OR for proteinuria in PD-IFG was 1.217 (1.140-1.300) and that in PD-Both was 1.249 (1.174-1.329), but that in PD-A1c was not significant, even after adjustment for significant covariates, such as age, sex, body mass index, systolic blood pressure, antihypertensive medication, eGFR, lifestyle and lipid profile.ConclusionsPrediabetes is a significant risk factor for proteinuria compared with completely normal glucose level, and subjects with prediabetes defined using IFG are at significantly higher risk for proteinuria than those defined by HbA1c only.