Prevalence of nephropathy in black patients with type 2 diabetes mellitus

Abstract

The prevalence of nephropathy in black patients with type 2 diabetes mellitus is poorly defined. We performed a cross-sectional analysis of 98 unrelated and unselected black type 2 diabetic patients treated in indigent care internal medicine clinics to determine the prevalence of proteinuria and nephropathy. Serum creatinine, blood urea nitrogen, urine albumin and urine creatinine concentrations were measured. A Spearman's rank correlation was computed to test for a relationship between diabetes duration and continuous outcomes. For binary outcomes, an odds ratio and 95% confidence interval were computed for a change of 10 years diabetes duration based on logistic regression. Cases were 61% female, and had mean (+/- SD) age 59.9 +/- 12.5 years, diabetes duration 12.6 +/- 9.4 years, body mass index 32.4 +/- 9.3 kg/m(2), hemoglobin A1C (HbA1C) 9.2 +/- 2.3%, and serum creatinine concentration 1.60 +/- 1.1 mg/dl. For continuous variables, diabetes duration was positively associated with albuminuria (r = 0.31; p = 0.0017), serum creatinine (r = 0.36; p = 0.0003) and blood urea nitrogen concentration (r = 0.36; p = 0.0003). For binary variables, cases with longer diabetes duration were at increased risk for urinary albumin:creatinine >300 microg/mg (p = 0.006), elevated serum creatinine concentration (> or = 1.4 mg/dl in women or > or = 1.6 mg/dl in men; p = 0.045), elevated blood urea nitrogen concentration (> or = 20 mg/dl; p = 0.026), and clinical cerebrovascular disease (p = 0.028). HbA1C, body mass index, and blood pressure did not correlate with diabetes duration in this population. Among the cases, 33.7% had elevated serum creatinine concentration and 71.5% had abnormal levels of albuminuria (27.6% > 300 microg albumin/mg Cr and 43.9% 30-300 microg albumin/mg Cr). Abnormal proteinuria was seen in the majority of black patients with poorly controlled type 2 diabetes mellitus treated in indigent care clinics. This prevalence may be conservative, due to the widespread use of angiotensin-converting enzyme inhibitor therapy and exclusion of cases treated only by nephrologists. Approximately 70% of black patients with type 2 diabetes cared for in indigent care clinics have abnormal proteinuria and are at heightened risk for ESRD and death.