Predictive value of albuminuria in American Indian youth with or without type 2 diabetes

Abstract

Objective: To examine the prognostic significance of elevated albuminuria in youth with type 2 diabetes.

Patients and methods: Cross-sectional and prospective studies were conducted on Pima Indian youth aged 5 to 19 years at baseline who were examined between July 1, 1982, and December 31, 2007. Prevalence and sequential changes in the level of microalbuminuria (30 < or = albumin-to-creatinine ratio [ACR] < 300 mg/g) and macroalbuminuria (ACR > or = 300 mg/g) and incidence of macroalbuminuria were computed according to the presence or absence of type 2 diabetes.

Results: The prevalence of microalbuminuria and macroalbuminuria was 6.5% and 0.6% in the 3856 nondiabetic youth and 18.5% and 2.9% in the 103 youth with diabetes, respectively. One hundred forty-one of 187 (75.4%) nondiabetic youth, but only 1 of 14 (7.1%) diabetic youth with an elevated ACR (> or =30 mg/g) regressed to an undetectable or normal ACR (<30 mg/g) on subsequent examination. In a subset of 2666 youth with a median follow-up of 8.1 years, 36 nondiabetic and 30 diabetic youth with baseline ACRs of <300 mg/g developed macroalbuminuria. For a given ACR, the incidence of macroalbuminuria was 15.9-fold (95% confidence interval: 11.1-22.6) higher in the diabetic than in the nondiabetic youth.

Conclusions: Elevated albuminuria is infrequent and largely transient in nondiabetic youth, but it is relatively frequent and largely persistent in those with diabetes. Microalbuminuria in youth with type 2 diabetes strongly predicts progression to macroalbuminuria, which supports annual screening for albuminuria.

Figure 1

Frequency distribution of several ACR categories in youth and adults without (A) or with type 2 diabetes (B). The hatched and black bars represent micro- and macroalbuminuria, respectively. UD represents undetectable albuminuria, in which case ACR cannot be calculated.

Figure 2

Unadjusted incidence rates of macroalbuminuria according to ACR categories in youth aged 5-19 years without diabetes (A) or with type 2 diabetes (B). UD represents undetectable albuminuria. Note the 10-fold difference in the y-axis scales between panels.