Glomerular filtration rate changes in normoalbuminuric and microalbuminuric Type 2 diabetic patients and normal individuals: A 10-year follow-up

Abstract

Aim To analyze the changes in the glomerular filtration rate (GFR) in a cohort of normoalbuminuric Type 2 diabetic (DM 2) patients and nondiabetic individuals. Methods Sixty-five normoalbuminuric DM 2 patients [urinary albumin excretion rate (UAER) <20 μg/min] and 44 nondiabetic individuals recruited at baseline were followed for a mean period of 10±1 years. In addition to conventional clinical and metabolic variables, GFR ( 51Cr-EDTA technique) and UAER (immunoturbidimetric method) measurements were performed at baseline and at follow-up. We also evaluated the presence of diabetic retinopathy, hypertension, and cardiovascular disease. Multiple linear regression was performed to assess variables independently associated with GFR evolution in patients with Type 2 diabetes. Results Fifty DM 2 patients and 32 nondiabetic individuals were included in the follow-up evaluation. Fourteen out of the 50 patients with Type 2 diabetes developed microalbuminuria. They presented a faster GFR decline (−0.39±0.24 ml/min/month; ANOVA, P=.0013) than did persistently normoalbuminuric (−0.16±0.16 ml/min/month) and nondiabetic individuals (−0.13±0.14 ml/min/month). Multiple linear regression analysis disclosed baseline fasting plasma glucose (FPG) along with the development of microalbuminuria as factors significantly related to a higher GFR decline. Conclusions Persistently normoalbuminuric patients and normal individuals presented a similar degree of GFR reduction related to the aging process. The slope was significantly enhanced in patients who developed microalbuminuria and was influenced by worse baseline glucose control.