Hyperfiltration a Risk Factor for Diabetic Nephropathy

According to a published study, in patients with type 2 diabetes, persistent glomerular hyperfiltration is associated with nephropathy and greater declines in renal function.

Piero Ruggenenti, M.D., from the Mario Negri Institute for Pharmacological Research in Bergamo, Italy, and colleagues analyzed the effect of the glomerular filtration rate (GFR) on GFR decline and nephropathy in 600 patients with type 2 diabetes and normo- or microalbuminuria from two randomized trials. Of these, 15 percent were hyperfiltering at inclusion (GFR of ≥120 mL/min/1.73 m²).

Over a median follow-up of four years the researchers found that the GFR fell by a median of 3.37 mL/min/1.73 m² per year. Patients who had a larger reduction in GFR at six months were more likely to have a slower subsequent decline, particularly patients who were hyperfiltering. Of hyperfiltering patients, progression to micro- or macroalbuminuria was more common in those with persistent hyperfiltration compared with those who became non-hyperfiltering or whose hyperfiltration had improved at six months (hazard ratio, 2.16). Amelioration of hyperfiltration was associated with improvements in blood pressure, metabolic control, and the glucose disposal rate, as well as slower long-term GFR decline, and was independent of baseline characteristics or angiotensin-converting-enzyme inhibition.

"Results of our observational post hoc analyses suggest that in hypertensive type 2 diabetic subjects with normo- or microalbuminuria, persistent hyperfiltration is an independent risk factor for accelerated renal function loss and development or progression of nephropathy, whereas amelioration of hyperfiltration is renoprotective," Ruggenenti and colleagues conclude.

Diabetes Care, July 6, 2012