Objective: We examined secular trends in the frequency distribution of albuminuria and estimated glomerular filtration rate (eGFR) in subjects with type 2 diabetes in 1982-1988 and 2001-2006, two periods associated with major changes in the management of diabetes.
Research design and methods: The cross-sectional study included Pima Indians > or =15 years old with type 2 diabetes and measures of serum creatinine and urinary albumin-to-creatinine ratios (ACR). The continuous probability density distributions of ACR and eGFR were compared for the two time periods. eGFR was calculated using the Modification of Diet in Renal Disease Study equation.
Results: The overall standardized distribution of ACR shifted toward lower values between time periods (P = 0.001), whereas the standardized distribution of eGFR did not (P = 0.45). In the first period, eGFR was <60 ml/min per 1.73 m(2) in 6.5% of the 837 subjects. Of these, 9.3% had normal ACR, 7.4% had microalbuminuria, and 83.3% had macroalbuminuria. In the second period, the prevalence of low eGFR was similar (6.6% of the 1,310 subjects). Among those with low eGFR, normal ACR prevalence doubled to 17.2%, microalbuminuria prevalence nearly tripled to 19.5%, and macroalbuminuria prevalence declined to 63.2%. Twice as many subjects in the second period received antihypertensive medicines and 30% more received hypoglycemic medicines than in the first period.
Conclusions: The distribution of albuminuria changed significantly among diabetic Pima Indians over the past 20 years, as treatment with medicines to control hyperglycemia and hypertension increased. The distribution of eGFR, however, remained unchanged. Consequently, the frequency of chronic kidney disease characterized by normoalbuminuria and low eGFR doubled.