Association of Estimated Glomerular Filtration Rate With Progression of Albuminuria in People With Type 2 Diabetes

  

OBJECTIVE: To elucidate the association of glomerular filtration rate (GFR) at baseline with subsequent albuminuria development and progression in people with type 2 diabetes.

RESEARCH DESIGN AND METHODS: This was a single-center, retrospective cohort study of 6,618 Japanese adults with type 2 diabetes and urinary albumin-to-creatinine ratio of <300 mg/g, comprising 2,459 women and 4,159 men with a mean (± SD) age of 60 ± 12 years. The exposure was a baseline estimated GFR (eGFR, mL/min/1.73m2), treated as a categorical variable classified into five categories: ≥90, 75-90, 60-75, 45-60 and <45, as well as a continuous variable. The outcome was the category progression of albuminuria (i.e., from normoalbuminuria to micro- or macroalbuminuria, or from micro- to macroalbuminuria). The hazard ratios for the outcome were estimated using the multivariable Cox proportional hazards model. In the analysis treating baseline eGFR as a continuous variable, the multivariable-adjusted restricted cubic spline model was used.

RESULTS: During the median follow-up period of 6.3 years, 1,190 reached the outcome. When people with a baseline eGFR of 75-90 mL/min/1.73m2 were considered the reference group, the hazard ratios (95% CI) for the outcome in those with a baseline eGFR of ≥90, 60-75, 45-60 and <45 mL/min/1.73m2 were 1.38 (1.14-1.66), 1.34 (1.14-1.58), 1.81 (1.50-2.20), and 2.37 (1.84-3.05), respectively. Furthermore, the inverse J-shaped curve was more clearly shown by the spline model.

CONCLUSIONS: This study of Japanese adults with type 2 diabetes suggests that both a high and low GFR are implicated in the pathogenesis of albuminuria development and progression.