Nonalbuminuric Renal Insufficiency in Type 2 Diabetes

Abstract

OBJECTIVE - To determine the prevalence and characteristics of patients with type 2 diabetes who have impaired renal function, defined as a glomerular filtration rate (GFR) <60 ml · min-1 · 1.73 m -2, and normoalbuminuria. RESEARCH DESIGN AND METHODS - A cross-sectional survey of 301 outpatients attending a single tertiary referral center using the plasma disappearance of isotopic 99mTc-diethylene-triamine-penta-acetic acid to measure GFR and at least two measurements of urinary albumin excretion rate (AER) over 24 h to determine albuminuria. RESULTS - A total of 109 patients (36%) had a GFR <60 ml · min-1 · 1.73 m-2. The overall prevalence of normo-, micro-, and macroalbuminuria was 43 of 109 (39%), 38 of 109 (35%), and 28 of 109 (26%), respectively. Compared with patients with macroalbuminuria, those with normoalbuminuria were more likely to be older and female. After excluding patients whose normoalbuminuric status was possibly related to the initiation of a renin-angiotensin system (RAS) inhibitor before the start of the study, the prevalence of a GFR <60 ml · min -1 · 1.73 m-2 and normoalbuminuria was 23%. Temporal changes in GFR in a subset of 34 of 109 (32%) unselected patients with impaired renal function were available for comparison over a 3- to 10-year period. The rates of decline in GFR (ml · min-1 · 1.73 m-2 · year-1) of -4.6 ± 1.0, -2.8 ± 1.0, and -3.0 ± 07 were not significantly different for normo- (n = 12), micro- (n = 12), and macroalbuminuric (n = 10) patients, respectively. CONCLUSIONS - These results suggest that patients with type 2 diabetes can commonly progress to a significant degree of renal impairment while remaining normoalbuminuric.