ADA: Renal Function Decline Begins
Earlier than Thought, in Type 1 Diabetics
Decline in renal functioning begins soon after
the onset of microalbuminuria in patients with
type 1 diabetes, which is contrary to widespread
the belief that decline in renal function decline
results from longstanding exposure to proteinuria.
"We found that even though there's a rate
of decline when people have advanced kidney disease,
we see that the pace of decline is set very early
around the time of their onset of microalbuminuria,"
said Bruce Perkins, MPH, lead researcher and fellow
at Joslin Diabetes Center, in Boston, Massachusetts.
"It means that there is a process of renal
function decline being initiated early."
The investigators studied data on 191 randomly
chosen subjects. Each subject had "at least
3 stored plasma specimens spanning 10 years of
follow-up from two groups in the Joslin Study
of the Natural History of Microalbuminuria (MA)
cohort. A total of 106 subjects had normal albuminuria
throughout the follow-up period ("NA Group"),
and 85 had onset of MA during follow-up ("MA
Onset Group")."
"The diagnosis of MA was based on the mean
of two or more measurements of albumin excretion
rate (AER) [ge] 30 mcg/min in a 2-year interval.
The reciprocal of plasma cystatin C is a valid
measure of glomerular filtration rate [GFR] in
type 1 diabetes that is able to detect changes
in GFR in the supranormal range. Changes in GFR
over the 10 years were linear, and the rate of
change was estimated by linear regression (R20=.91)
and expressed as percent change per year,"
the researchers stated in their poster.
"GFR change was minor in the NA Group, and
the variability was not explained by any clinical
factor. In contrast, there was significant renal
function decline in the MA Onset Group (P<0.001).
Clinically significant renal function decline,
defined as a GFR decline [ge]5% per year based
on the NA group distribution, occurred in 25%
of the MA Onset Group. In the MA onset group,
AER at baseline was the same regardless of whether
renal function subsequently declined. The means,
however, diverged during follow-up from 71 up
to 258 mcg/min and 52 down to 44 mcg/min for those
with and without decline, respectively. Renal
function decline was not associated with diabetes
duration but was associated with higher HbA1c
and serum cholesterol (p=0.03 and 0.07, respectively),"
the researchers wrote.
Based upon this data, the authors concluded that
decline in renal function starts soon after the
onset of microalbuminuria. This finding is contrary
to widespread the belief that decline in renal
function decline results from longstanding exposure
to proteinuria.
"Since we know the process starts earlier
then we should probably be applying treatments
or preventive therapies earlier as well,"
said Perkins.
Presentation at the American Diabetes Association
63rd Annual Meeting. [Study title: Abstract Title
Renal Function Decline Occurs Soon after the Onset
of Microalbuminuria in Type 1 Diabetes. Abstract
812]
====================================================
FACT: Type 2 diabetes increases the risk
of cardiovascular disease between two and six-fold,
and shortens life expectancy by 5 to 10 years.
Once a person with diabetes has developed severe
vascular complications, they will survive just
five years on average. Diabetes Voice May 2003
volume 48
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