Research Articles in Diabetes and Diabetic
Retinopathy
The Wisconsin Epidemiologic Study of Diabetic Retinopathy: XVII The
14-year Incidence and Progression of Diabetic Retinopathy and Associated Risk Factors in
Type I Diabetes
(From Ophthalmology 1998;105:1801-1815, Klein R, MD, et al.)
OVERVIEW:
This study is a 14 year follow-up of the Wisconsin Epidemiologic Study of Diabetic
Retinopathy. (The 10 year follow-up study is discussed on a
separate page on this site.) The objective of the study is to examine the 14 year
incidence and progression of diabetic retinopathy and macular edema, and its relation to
various risk factors. While the 10 year study looked at both Type I and Type II diabetics,
this study looked only at the Type I diabetics (634 insulin taking individuals diagnosed
before the age of 30). These individuals participated in baseline, 4 year, 10 year, and 14
year examinations. Medical factors, such as hypertension, control of blood sugar,
proteinuria, and cigarette smoking, were looked at well.
RESULTS:
Overall, the incidence and rate of progression of diabetic retinopathy was high:
-
By 14 years, 95.9% of individuals had some retinopathy.
-
85.6% of individuals had progression (worsening) of retinopathy.
-
36.8% of individuals had progression to proliferative retinopathy.
-
13.3% of individuals had progression to proliferative retinopathy with high risk
characteristics.
-
26.1% of individuals had macular edema, and 17% had clinically significant macular
edema.
The highest rate in the progression of retinopathy (94.2%) was in those 19 years of age
or younger at baseline, while the lowest rate of progression (68.1%) was in those who were
35 years or older. Through the first 10 years of follow-up, no individual who was younger
than 10 at baseline developed proliferative disease. However, by 14 years of follow-up, 6%
developed proliferative disease, and 10% had macular edema. Many studies have shown this
relative protective effect seen in the years before puberty in children with diabetes.
Of the 227 individuals found to have proliferative disease in at least one eye at
baseline, 52% had died by the 14 year follow-up.
Glycosylated hemoglobin (HbA1c) level at baseline was found to be a significant
predictor of progression of retinopathy, progression to proliferative disease, and
incidence of macular edema. These findings were independent of the duration of diabetes
and of the severity of retinopathy at baseline. Furthermore, a 1 percentage point decrease
in the HbA1c level from baseline to the 4 year follow-up was found to lead to a 25%
decrease in the 14 year incidence of proliferative retinopathy and macular edema.
Diastolic blood pressure was found to be a predictor of progression of retinopathy, and
hypertension a predictor of proliferative retinopathy in this Type I diabetes group. A 10
mmHg increase in diastolic blood pressure from the baseline to the 4 year follow-up was
associated with a 35% increase in the 14 year progression of retinopathy. This was
independent of glycosylated hemoglobin, age at examination, and severity of retinopathy at
baseline.
There was found to be no relationship between diuretic use and progression of
retinopathy, nor was there any relationship between cigarette smoking and progression of
retinopathy.
CONCLUSIONS:
This study shows a high rate of diabetic retinopathy in Type I diabetics. There is a
suggestions that better glycemic control at any time during the course of diabetes, and
that control of blood pressure may be beneficial in reducing the incidence of macular
edema and the progression to proliferative disease.
For information about diabetic eye disease in general, and
for an explanation of terminology used below, go to
Diabetic Eye Disease.
Return to the List of Diabetes
Articles
