Diabetes Care, Vol 23, Issue 1 51-56, Copyright © 2000 by American Diabetes Association
Trends in persistent proteinuria in adult-onset diabetes: a population-based study
TS Larson, N Santanello, S Shahinfar, PC O'Brien, PJ Palumbo, LJ Melton and CL Leibson
Division of Nephrology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA. larson.timothy@mayo.edu
OBJECTIVE: This study investigates temporal trends in the prevalence and
incidence of persistent proteinuria among people with adult-onset diabetes
(age > or =40 years). RESEARCH DESIGN AND METHODS: The complete
community-based medical records of all Rochester, Minnesota, residents with
a diagnosis of diabetes or diabetes-like condition from 1945 through 1989
were reviewed to determine whether they met National Diabetes Data Group
(NDDG) criteria. All confirmed diabetes cases residing in Rochester on 1
January 1970 (n = 446), 1980 (n = 647), and/or 1990 (n = 940) were
identified. The medical records of these prevalence cases were reviewed
from the time of the first laboratory urinalysis value to the last visit,
death, or 1 April 1992 (whichever came first) for evidence of persistent
proteinuria (two consecutive urinalyses positive for protein, with no
subsequent negative values). Similarly, the medical records of all
1970-1989 diabetes incidence cases (n = 1,252) were reviewed to investigate
temporal changes in 1) the likelihood of having persistent proteinuria
before the date NDDG criteria was met, i.e., baseline; 2) the risk of
persistent proteinuria after baseline; and 3) the relative risk of
mortality associated with persistent proteinuria. RESULTS: The proportion
of diabetes prevalence cases with persistent proteinuria on or before the
prevalence date declined from 20% in 1970 to 11% in 1980 and 8% in 1990.
Among the 1970-1989 diabetes incidence cases, 77 (6%) had persistent
proteinuria on or before baseline; the adjusted odds declined by 50% with
each 10-year increase in baseline calendar year (P<0.001). Among
individuals free of persistent proteinuria at baseline, 136 subsequently
developed persistent proteinuria; the estimated 20-year cumulative
incidence was 41% (95% CI 31-59); the adjusted risk did not differ as a
function of baseline calendar year. Survival of individuals with persistent
proteinuria relative to those without was reduced but did not differ by
baseline calendar year. CONCLUSIONS: The prevalence of persistent
proteinuria among people with adult-onset diabetes in Rochester, Minnesota,
declined 60% between 1970 and 1990. The decline appears because of a
decrease in the proportion of diabetes incidence cases with persistent
proteinuria before baseline rather than secular declines in the risk of
persistent proteinuria after baseline or secular increases in the risk of
mortality associated with persistent proteinuria. Similarity over time in
age and fasting glucose at baseline, and at prevalence dates, is evidence
that earlier detection of diabetes is not the sole explanation for the
decline.