Diabetes, Vol 44, Issue 2 161-164, Copyright © 1995 by American Diabetes Association
Does insulin-like growth factor I predict incidence and progression of diabetic retinopathy?
Q Wang, DG Dills, R Klein, BE Klein and SE Moss
Department of Ophthalmology and Visual Sciences, University of Wisconsin Medical School, Madison.
We evaluated the relationship of insulin-like growth factor (IGF)-I to
incidence and progression of diabetic retinopathy over a 6-year interval in
a large population-based study of diabetes in southern Wisconsin.
Participants included people with younger-onset diabetes (n = 66
adolescents, n = 661 adults > or = 18 years of age) and older-onset
diabetes (n = 285 for those using insulin, n = 248 for those not using
insulin). Fundus photographs were graded in a masked fashion using
standardized protocols to determine the severity of retinopathy in each
eye. Serum IGF-I levels were measured during 1984-1986 using a
double-antibody radioimmunoassay. Mean IGF-I was highest in adolescents
(499.1 micrograms/l), lower in younger-onset adult (280.1 micrograms/l),
and lowest in the older-onset group (205.7 and 221.2 micrograms/l for
older-onset group using insulin and not using insulin, respectively). The
incidence of retinopathy was not significantly higher in people with higher
IGF-I levels in any group. The odds of developing diabetic retinopathy in 6
years for each 10 micrograms/l increase in IGF-I after controlling for age,
glycosylated hemoglobin, and duration of diabetes at baseline was 1.21 (95%
confidence interval [CI] 0.95-1.54) for adolescents; 1.00 (95% CI
0.93-1.08) for younger-onset adults; 0.93 (95% CI 0.85-1.02) for the
older-onset group using insulin; and 0.99 (95% CI 0.95-1.04) for the
older-onset group not using insulin. In summary, IGF-I was not associated
with 6-year incidence or progression of diabetic retinopathy in any of the
groups.