Differences in risk factors for the onset of albuminuria and decrease in glomerular filtration rate in people with Type 2 diabetes mellitus: implications for the pathogenesis of diabetic kidney disease

AIMS To determine differences in predictors of albuminuria and decreased estimated GFR in Japanese people with Type 2 diabetes mellitus without chronic kidney disease. METHODS This single-centre observational cohort study involved 1802 Japanese people with Type 2 diabetes with normoalbuminuria and estimated GFR ≥ 60 ml/min/1.73 m(2) (740 women; mean ± sd age 58 ± 12 years). Two separate outcomes were evaluated: onset of albuminuria ( ≥ 30 mg/g creatinine, albuminuria cohort; n = 1655) and decrease in estimated GFR ( < 60 ml/min/1.73 m(2) ; estimated GFR cohort; n = 1777). A Cox proportional hazards model was used to identify significant predictors for each outcome. RESULTS During a median follow-up period of 6.9 years for the albuminuria cohort and 8.0 years for the estimated GFR cohort, 181 and 316 individuals reached the respective outcome. The 5-year cumulative incidence of albuminuria was 8.3%, and that of decreased estimated GFR was 10.4%. In the multivariate Cox model, greater urinary albumin-to-creatinine ratio, presence of diabetic retinopathy and higher HbA1c levels were associated with both outcomes. Unique risk factors for onset of albuminuria were male gender and higher uric acid levels; those for decreased estimated GFR were older age, greater systolic blood pressure, and lower baseline estimated GFR and HDL cholesterol levels. CONCLUSIONS Identification of both common and distinct predictive factors for onset of albuminuria and decreased estimated GFR support the hypothesis that both common and distinct pathophysiological mechanisms are involved in the development of these two manifestations of chronic kidney disease in diabetes.