Renal Insufficiency in the Absence of Albuminuria and Retinopathy Among Adults with Type 2 Diabetes Mellitus

Context: Kidney disease in type 2 diabetes mellitus (DM) is more heterogeneous than in type 1 DM. Reduced glomerular filtration rate (GFR) among individuals with type 2 DM may not always be due to classic diabetic glomerulosclerosis, which is associated with albuminuria and retinopathy.

Objective: To determine the prevalence of chronic renal insufficiency (CRI), defined as a GFR less than 60 mL/min per 1.73 m2 body surface area (BSA) in the absence of microalbuminuria or macroalbuminuria and diabetic retinopathy among adults with type 2 DM.

Design, Setting, And Participants: Cross-sectional analysis of adults aged 40 years or older with type 2 DM in the Third National Health and Nutrition Examination Survey, a probability sample of the total civilian US noninstitutionalized population conducted from 1988-1994.

Main Outcome Measures: The GFR per 1.73 m2 BSA, calculated with serum creatinine, urea nitrogen, and serum albumin levels using the Modification of Diet in Renal Disease Study prediction equation; albuminuria, assessed using spot urine albumin/creatinine ratio; and presence of retinopathy, determined with fundus photography.

Results: Overall, 13% (sampled n = 171) of adults with type 2 DM (n = 1197) had CRI with a population estimate of 1.1 million. Among these adults with CRI, diabetic retinopathy was noted in 28% (n = 58), while the frequencies of microalbuminuria and macroalbuminuria were 45% (n = 64) and 19% (n = 47), respectively. Retinopathy and albuminuria (microalbuminuria or macroalbuminuria) were both absent in 30% (n = 51) of adults with type 2 DM and CRI. The population estimate of adults with type 2 DM and CRI in the absence of diabetic retinopathy or albuminuria was approximately 0.3 million.

Conclusions: A substantial burden of CRI among persons with type 2 DM in the United States is likely due to renal parenchymal disease other than classic diabetic glomerulosclerosis. Approaches to screening renal disease in the type 2 DM population should incorporate assessment of GFR in addition to monitoring urine albumin excretion and funduscopic changes to ensure that individuals with type 2 DM and CRI not due to diabetic glomerulosclerosis will receive appropriate intervention.