Renal Dysfunction in Prediabetes: Confirmed by Glomerular Hyperfiltration and Albuminuria

Abstract

Objectives Prediabetes is defined as an intermediate state of hyperglycemia with glucose levels above normal but below the diagnostic cutoff of diabetes mellitus. Prediabetes is considered as an important risk factor for the development of diabetes and complications associated with diabetes. Since glomerular hyperfiltration (elevated GFR) and albuminuria represent early and reversible stages of kidney damage seen in patients with type 2 diabetes, we aim to assess the impact of hyperglycemia in prediabetic range on renal functions measured by estimated GFR and urine albumin excretion (UAE). Materials and Methods The study included 1,031 patients aged 30 to 70 years, attending regular health checkup. Patients were grouped as normal, prediabetes, and diabetes according to the American Diabetic Association (ADA) criteria based on fasting blood sugar and hemoglobin A1c (HbA1c). Further, the patients were grouped into multiple subgroups based on age and gender. UAE was measured by using immunoturbidimetric method, and GFR was estimated by chronic kidney disease epidemiology collaboration (CKD EPI) equation. Statistical Analysis Prevalence of hyperfiltration (estimated glomerular filtration rate above the age and gender specific 95th percentile), and albuminuria in prediabetes and diabetes was compared with normal controls. Odds ratio and 95% confidence interval were calculated by using logistic regression analysis to predict the occurrence of hyperfiltration in prediabetes and diabetes. Analysis of variance followed by post hoc comparison was done to assess the significance of difference, and p -value < 0.05 was considered statistically significant. Results Prevalence of hyperfiltration was more in prediabetes and diabetes compared with normal controls, and it increased with surging HbA1c level that was shown as higher odds ratio for hyperfiltration in both the groups. UAE was more in the prediabetes and diabetes group when compared with normal controls, but the difference was significant only in diabetes. Conclusion Since glomerular hyperfiltration represents an early and reversible stage of renal damage manifesting before the appearance of albuminuria, elevated GFR can be used to identify asymptomatic patients with intermediate hyperglycemia having high risk of developing nephropathy in the future. Prediabetes represents a window of opportunity to initiate preventive strategies at an early stage before the occurrence of significant renal damage.