Glomerular hyperfiltration and renal disease progression in type 2 diabetes

OBJECTIVE - To describe the prevalence and determinants of hyperfiltration (glomerular filtration rate [GFR] ≥120 mL/min/1.73 m²), GFR decline, and nephropathy onset or progression in type 2 diabetic patients with normo- or microalbuminuria. RESEARCH DESIGN AND METHODS - We longitudinally studied 600 hypertensive type 2 diabetic patients with albuminuria 1c was 2 per year. GFR change was bimodal over time: a larger reduction at 6 months significantly predicted slower subsequent decline (coefficient: -0.0054; SE: 0.0009), particularly among hyperfiltering patients. A total of 90 subjects (15%) were hyperfiltering at inclusion, and 11 of 47 (23.4%) patients with persistent hyperfiltration progressed to micro- or macroalbuminuria versus 53 (10.6%) of the 502 who had their hyperfiltration ameliorated at 6 months or were nonhyperfiltering since inclusion (hazard ratio 2.16 [95% CI 1.13-4.14]). Amelioration of hyperfiltration was independent of baseline characteristics or ACE inhibition. It was significantly associated with improved BP and metabolic control, amelioration of GDR, and slower long-term GFR decline on follow-up. CONCLUSIONS - Despite intensified treatment, patients with type 2 diabetes have a fast GFR decline. Hyperfiltration affects a subgroup of patients and may contribute to renal function loss and nephropathy onset or progression. Whether amelioration of hyperfiltration is renoprotective is worth investigating.