High-normal levels of albuminuria predict the development of micro- and macroalbuminuria and increased mortality in Brazilian Type 2 diabetic patients: an 8-year follow-up study.

AIM: To analyse the risk factors for the development of micro- and macroalbuminuria and mortality rates in a cohort of normoalbuminuric Type 2 diabetes mellitus (DM) patients.
METHODS: In this prospective study, 193 Type 2 DM patients with urinary albumin excretion (UAE) < 20 microg/min, 96 men (50%), aged 56.5 +/- 9 years, were followed for a mean period of 8 +/- 3 years. UAE and estimated glomerular filtration rate (eGFR; Modification of Diet in Renal Disease) were measured. The outcomes were development of persistent micro- and macroalbuminuria and mortality.
RESULTS: Twenty patients were lost to follow-up. Of the 173 remaining patients, 33 (19%) died. The Cox analysis [hazard ratio (HR), 95% confidence interval] revealed that the baseline significant predictors of mortality were higher UAE [above median (5 microg/min); HR 2.7, 1.2-6.1; P = 0.02], male sex (HR 3.9, 1.7-9.2; P = 0.002), age (HR 1.6, 1.3-1.9; P = 0.0001), and fasting plasma glucose (HR 1.2, 1.1-1.3; P = 0.004). Smoking and eGFR were not significant in this model. Follow-up renal data were available for 158 patients: 34 (22%) progressed to microalbuminuria and seven (4%) to macroalbuminuria, and the baseline predictors were a higher UAE (> 5 microg/min, HR 2.5, 1.2-5.1; P = 0.02), presence of diabetic retinopathy (HR 2.5, 1.3-5.0; P = 0.009), fasting glucose (HR 1.1, 1.0-1.2; P = 0.015), and male sex (HR 2.2, 1.1-4.7; P = 0.04), independently of smoking and hypertension. Lower GFR (HR 0.98, 0.97-1.00; P = 0.07) was of borderline significance.
CONCLUSIONS: In normoalbuminuric Type 2 DM patients, the development of micro- or macroalbuminuria and mortality rates was independently and positively associated with higher levels of albuminuria, although still in the traditionally established normal range.