Aims/hypothesis: Glomerular hyperfiltration is a well-established phenomenon occurring early in some patients with type 1 diabetes. However, there is no consistent answer regarding whether hyperfiltration predicts later development of nephropathy. We performed a systematic review and meta-analysis of observational studies that compared the risk of developing diabetic nephropathy in patients with and without glomerular hyperfiltration and also explored the impact of baseline GFR.
Methods: A systematic review and meta-analysis was carried out. Cohort studies in type 1 diabetic participants were included if they contained data on the development of incipient or overt nephropathy with baseline measurement of GFR and presence or absence of hyperfiltration.
Results: We included ten cohort studies following 780 patients. After a study median follow-up of 11.2 years, 130 patients had developed nephropathy. Using a random effects model, the pooled odds of progression to a minimum of microalbuminuria in patients with hyperfiltration was 2.71 (95% CI 1.20-6.11) times that of patients with normofiltration. There was moderate heterogeneity (heterogeneity test p = 0.05, measure of degree of inconsistency = 48%) and some evidence of funnel plot asymmetry, possibly due to publication bias. The pooled weighted mean difference in baseline GFR was 13.8 ml min(-1) 1.73 m(-2) (95% CI 5.0-22.7) greater in the group progressing to nephropathy than in those not progressing (heterogeneity test p < 0.01).
Conclusions/interpretation: In published studies, individuals with glomerular hyperfiltration were at increased risk of progression to diabetic nephropathy using study level data. Further larger studies are required to explore this relationship and the role of potential confounding variables.