Clinical Significance of Decreased Glomerular Filtration Rate (GFR) without Albuminuria among Type 2 Diabetics

Background: Microalbuminuria in type 2 diabetes is a predictor of development of clinical nephropathy and cardiovascular disease. But, it has been reported that reduced glomerular filtration rate (GFR) may occur in some normoalbuminuric diabetic patients. The aim of this study was to identify whether decreased GFR without microalbuminuria is to predict diabetic vascular complications. Methods: Between January 1998 and February 2001, 73 patients with type 2 diabetes who visited Yeungnam university medical center were divided into 5 groups according to initial GFR ranges: group 1 (GFR < 30 mL/min), group 2 (30 ≤ GFR < 60 mL/min), group 3 (60 ≤ GFR < 90 mL/min), group 4 (90 ≤ GFR < 125 mL/min), group 5 (125 mL/min ≤ GFR). They were examined for microvascular and macrovascular complications initially and after 4 years. Results: Decreased GFR had a negative correlation with age (r = -0.472, P = 0.001). Decreased GFR without microalbuminuria had a significant correlation with development of diabetic nephropathy (P = 0.016) after 4 years. There were no significant correlation with the prevalence of diabetic retinopathy, peripheral neuropathy, and macrovacular disease. But, our study showed that coronary artery disease had an increasing tendency with decreased GFR without statistical significance (P = 0.085). Conclusions: Our data suggest that reduced GFR, independent of albuminuria, may be an important predictor of diabetic nephropathy and coronary artery disease t o some extent. So we recommend that not only the microalbuminuria, but also the decrease in GFR should be evaluated at the follow-up of patients with type 2 diabetes. (KOREAN DIABETES J 32:252-258, 2008)