Glomerular hyperfiltration usually occurs early in development of kidney complications in diabetes. To understand hyperfiltration as a marker of renal disease progression in type 2 diabetes mellitus, we aimed to examine association between glomerular hyperfiltration (estimated glomerular filtration rate ≥ 120 mL/min/1.73 m2) and rapid renal decline (annual estimated glomerular filtration rate loss ≥ 3 mL/min/1.73 m2).Methods:
This was a prospective cohort comprising 1014 patients with type 2 diabetes mellitus attending a Diabetes Centre of a regional hospital in 2002–2014. A separate prospective cohort, comprising 491 patients who attended Diabetes Centre or primary-care polyclinics, was used for validation. We performed binary mediation analysis to examine role of hyperfiltration on relationship between baseline haemoglobin A1c and rapid renal decline.Results:
Among patients in discovery cohort, 5.2% had baseline hyperfiltration. Over mean follow-up of 6 years, 22.9% had rapid glomerular filtration rate decline. Baseline hyperfiltration was significantly associated with greater odds of rapid renal decline after adjusting for demographics, diabetes duration and clinical covariates (odds ratio: 2.57; 95% confidence interval: 1.21–5.46; p = 0.014). Similar finding was found in validation cohort (odds ratio: 2.98; 95% confidence interval: 1.06–8.42; p = 0.034). Hyperfiltration significantly accounted for 35.3% of association between increasing baseline haemoglobin A1c and rapid renal decline.Conclusion:
Glomerular hyperfiltration is an independent risk factor of rapid renal decline. It mediates the association between increasing haemoglobin A1c and rapid renal decline.