title: Elevated baseline glomerular filtration rate (GFR) is independently associated with a more rapid decline in renal function of patients with type 1 diabetes.
abstract: OBJECTIVE
  Renal hyperfiltration is observed prior to the development of diabetic kidney disease (DKD) in patients with type 1 diabetes (T1DM); however its significance remains uncertain. Longitudinal data were used to investigate the association between measured baseline glomerular filtration rate (GFR) and renal function decline in patients with T1DM.
  
  
  METHODS
  This study included 142 adult patients with T1DM and ≥2 measurements of glomerular filtration rate (mGFR; determined by diethylene-triamine-penta-acetic acid plasma clearance). Median follow up was 19 years. Patients were stratified by baseline mGFR quartile. The relationship between baseline mGFR and rate of renal function decline was assessed using random-effect generalized least squares regression, adjusted for age, duration of diabetes, HbA1c, blood pressure, renin-angiotensin-aldosterone system inhibitor therapy, LDL and BMI.
  
  
  RESULTS
  The average rates of decline in renal function for the 2nd (baseline mGFR: 96.4-112.6 ml min-(1) 1.73 m-(2)), 3(rd) (baseline mGFR: 112.6-125.5 ml min- (1) 1.73 m-(2)) and 4th quartiles (baseline mGFR >125.5 ml min-(1) 1.73 m-(2)) were significantly faster than the first quartile (baseline mGFR: 60.9-96.4 ml min-(1) 1.73 m-(2)). In further detail, the average rates of decline in the 2nd (rate of decline 1.25 ml min- (1) 1.73 m-(2) per year, 95% CI: 0.97; 1.52, p=0.008), 3rd (rate of decline 1.35 ml min-(1) 1.73 m-(2) per year, 95% CI: 1.08; 1.62, p= 0.001) and 4th quartiles (rate of decline 1.6 ml min-(1) 1.73 m-(2) per year, 95% CI: 1.34, 1.88, <0.0001) were significantly faster when compared to the first quartile (rate of decline 0.67 ml min-(1) 1.73 m-(2) per year, 95% CI: 0.37; 0.96). Sub-analysis of quartile 4 revealed higher HbA1c measurements throughout follow-up in those with rapid mGFR decline (>3.0 ml min(-1)1.73 m(-2)/year).
  
  
  CONCLUSIONS
  In patients with T1DM, higher baseline mGFR is associate ed with more rapid mGFR decline. Patients with high baseline mGFR who developed rapid mGFR decline had higher HbA1c measurements throughout the study. These findings are consistent with the concept that poor glycaemic control over time may be a determining factor for the rapid renal function decline observed in some hyperfiltering patients.
authors.affiliation: Austin Health Endocrine Centre, Heidelberg, Melbourne, VIC, Australia.
authors.forename: Hilary J
authors.initials: HJ
authors.lastname: Thomson
authors.affiliation: Austin Health Endocrine Centre, Heidelberg, Melbourne, VIC, Australia; Department of Medicine, Austin Health, The University of Melbourne, Melbourne, VIC, Australia; Menzies School of Health-Darwin, Casuarina NT 0810, Australia. Electronic address: elif.ekinci@unimelb.edu.au.
authors.forename: Elif I
authors.initials: EI
authors.lastname: Ekinci
authors.affiliation: Department of Medicine, Austin Health, The University of Melbourne, Melbourne, VIC, Australia; Austin Clinical School, Heidelberg, VIC, Australia.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Radcliffe
authors.affiliation: Austin Health Endocrine Centre, Heidelberg, Melbourne, VIC, Australia.
authors.forename: Jas-mine
authors.initials: JM
authors.lastname: Seah
authors.affiliation: Department of Endocrinology & Diabetes, St Vincent's Hospital, VIC, Australia; Department of Medicine, St Vincent's Health, The University of Melbourne, VIC, Australia.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: MacIsaac
authors.affiliation: Austin Health Endocrine Centre, Heidelberg, Melbourne, VIC, Australia; Department of Medicine, Austin Health, The University of Melbourne, Melbourne, VIC, Australia.
authors.forename: George
authors.initials: G
authors.lastname: Jerums
authors.affiliation: Austin Health Endocrine Centre, Heidelberg, Melbourne, VIC, Australia; Department of Medicine, Austin Health, The University of Melbourne, Melbourne, VIC, Australia.
authors.forename: Erosha
authors.initials: E
authors.lastname: Premaratne
mesh_terms: D000328:Adult; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000503:physiopathology; D003928:Diabetic Nephropathies / Q000503:physiopathology*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged
chemical_list: D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human
keywords: Diabetes; Diabetic kidney disease; Diabetic nephropathy; Hyperfiltration; Kidney