Increased risk of glomerular hyperfiltration in subjects with impaired glucose tolerance and newly diagnosed diabetes

BackgroundGlomerular hyperfiltration is closely related to diabetes and may lead to subsequent nephropathy, but the association between glomerular hyperfiltration and prediabetic state is unclear. We examined the relationship of different glycemic statuses, including normal glucose tolerance (NGT), isolated impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and newly diagnosed diabetes (NDD), with glomerular hyperfiltration. MethodsThis study included 12 833 subjects ≥20 years of age without a history of renal disease, cancer, moderate/severe anemia or diabetes and taking medications for hypertension, diabetes, hyperlipidemia or cardiovascular disease from National Cheng Kung University Hospital between January 2000 and August 2009. Hyperfiltration was defined as an estimated GFR (eGFR) above the age- and gender-specific 95th percentile for apparently healthy subjects, while hypofiltration was defined as an eGFR below the 5th percentile. eGFR was assessed using the Chronic Kidney Disease Epidemiology Collaboration equation. ResultsAfter further excluding hypofiltration and adjusting for available confounders, fasting plasma glucose (FPG), 2-hour postload glucose (2hPG), 2hPG-FPG (fluctuating blood glucose), HbA1c (average blood glucose), NDD and IGT but not isolated IFG were significantly associated with increased eGFR and a higher risk of hyperfiltration {NDD: odds ratio [OR] 1.97 [95% confidence interval (CI), 1.48-2.64], P < 0.001; IGT: OR 1.34 (95% CI 1.07-1.66), P = 0.009}. ConclusionsHigh glucose states increase hyperfiltration risk. In addition to newly diagnosed diabetes, excessively high GFR also deserves attention in subjects with IGT.