Published in:
01-12-2005 | Article
Renal hyperfiltration in type 2 diabetes: effect of age-related decline in glomerular filtration rate
Authors:
E. Premaratne, R. J. MacIsaac, C. Tsalamandris, S. Panagiotopoulos, T. Smith, G. Jerums
Published in:
Diabetologia
|
Issue 12/2005
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Abstract
Aims/hypothesis
We sought to characterise the effect of the age-related decline of GFR on hyperfiltration in type 2 diabetes and to identify clinical characteristics associated with hyperfiltration.
Materials and methods
GFR was measured in 662 type 2 diabetic patients by plasma disappearance of 99 m-technetium-diethylene-triamine-penta-acetic acid. The prevalence of hyperfiltration was calculated using both an age-unadjusted GFR threshold of >130 ml min−1 1.73 m−2 and an age-adjusted threshold incorporating a decline of 1 ml min−1 year−1 after the age of 40. The hyperfiltering patients were compared with type 2 diabetic subjects who had a GFR between 90 and 130 ml min−1 1.73 m−2 and were matched for age, sex and disease duration to allow for identification of modifiable factors associated with hyperfiltration.
Results
The prevalence of hyperfiltration was 7.4% when age-unadjusted and 16.6% when age-adjusted definitions were used. The age-unadjusted vs -adjusted prevalence rates for hyperfiltration were 50 vs 50%, 12.9 vs 23.4% and 0.3 vs 9.0% for patients aged <40 years, 40 to 65 years and >65 years, respectively. Both the age-unadjusted and -adjusted hyperfiltration groups had lower mean diastolic blood pressure and lower serum creatinine levels than the control groups. Although the age-unadjusted hyperfiltration group had larger kidneys compared to the control group, this difference was no longer significant when the age-adjusted definition was used. There were no differences in HbA1c, mean arterial pressure, antihypertensive use, insulin therapy, dyslipidaemia, frequency of macro- or microvascular complications, BMI, urinary sodium, urea and albumin excretion between the groups.
Conclusions/interpretation
Hyperfiltration was still more common among younger patients with type 2 diabetes even after adjusting for the expected age-related decline in GFR. Hyperfiltration was associated with a lower mean diastolic blood pressure independent of age.