Renal hyperfiltration and the development of microalbuminuria in type 1 diabetes

  1. Linda H Ficociello, DSc1,2,
  2. Bruce A Perkins, MD, MPH3,
  3. Bijan Roshan, MD1,4,
  4. Janice M Weinberg, ScD2,
  5. Ann Aschengrau, ScD2,
  6. James H Warram, MD, ScD1 and
  7. Andrzej S Krolewski, MD, PhD (Andrzej.krolewski{at}joslin.harvard.edu)1,4
  1. 1Research Division, Joslin Diabetes Center, Boston, Massachusetts
  2. 2School of Public Health, Boston University, Boston, Massachusetts
  3. 3Department of Endocrinology and Metabolism, Toronto General Hospital, Toronto, ON, Canada
  4. 4Harvard Medical School, Boston, Massachusetts

    Abstract

    Objective: To examine prospectively whether renal hyperfiltration is associated with the development of microalbuminuria (MA) in patients with type 1 diabetes, after taking into account known risk factors.

    Research Design and Methods: The study group is comprised of 426 participants with normoalbuminuria from the First Joslin Kidney Study, followed for 15 years. Glomerular filtration rate was estimated by serum cystatin C and hyperfiltration was defined as exceeding the 97.5th percentile of the sex-specific distribution of a similarly aged, non-diabetic population (134 for men and 149 ml/min/1.73m2 for women). The outcome was time to MA development (multiple albumin excretion rate > 30 μg/min). Hazard ratios (HRs) for MA were calculated at 5, 10 and 15 years.

    Results: Renal hyperfiltration was present in 24% of the study group and did not increase the risk of developing MA. The unadjusted HR for MA comparing those with and without hyperfiltration at baseline was 0.8 (95% CI: 0.4, 1.7) during the first 5 years, 1.0 (95% CI: 0.6, 1.7) during the first 10 years, and 0.8 (95% CI: 0.5, 1.4) during 15 years of follow-up. The model adjusted for baseline known risk factors including HbA1c, age at diagnosis of diabetes, diabetes duration, and cigarette smoking resulted in similar HRs. In addition, incorporating changes in hyperfiltration status during follow-up had minimal impact on the HRs for MA.

    Conclusions: Renal hyperfiltration does not have an impact on the development of MA in type 1 diabetes during 5, 10 or 15 years of follow-up.

    Footnotes

      • Received August 25, 2008.
      • Accepted January 20, 2009.

    This Article

    1. Published online before print February 5, 2009, doi: 10.2337/dc08-1560
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