The Wisconsin epidemiologic study of diabetic retinopathy XV : the long-term incidence of macular edema

As part of a population-based study of diabetes mellitus, the incidence of macular edema over a 10-year period and its relation to various risk factors are examined. There were 891 younger-onset people with a diagnosis of having had diabetes before 30 years of age who were taking insulin at baseline examination and 987 older-onset people with a diagnosis of having had diabetes at 30 years of age or older who participated in baseline and 4-year examinations. Of these, 765 younger-onset and 533 older-onset people also participated in a 10-year examination. The presence of macular edema at baseline and follow-up examinations was determined from gradings of stereoscopic fundus photographs. The incidence of macular edema over the 10-year period was 20.1% in the younger-onset group, 25.4% in the older-onset group taking insulin, and 13.9% in the older-onset group not taking insulin. The incidence of macular edema over the 10-year period was associated with higher levels of glycosylated hemoglobin and more severe retinopathy in both younger- and older-onset groups, and with being female and increased diastolic blood pressure in the older-onset group. These data suggest a relatively high incidence of macular edema. The authors' data also suggest that a reduction in hyperglycemia may result in a beneficial decrease in the incidence of macular edema.