Background: The etiology of diabetic retinopathy is poorly understood. In the current study, factor associated with the onset and the progression or regression of retinopathy are evaluated.
Methods: Two hundred seventy-seven subjects with insulin-dependent (type I) diabetes mellitus (IDDM) were evaluated longitudinally for retinal changes over a mean of 2.7 years. The multistate Markov model was used to analyze the influences of the duration of diabetes, a family history of hypertension, age, sex, cigarette smoking, systolic blood pressure, diastolic blood pressure, cholesterol levels, and longitudinal glycohemoglobin (GHb) values on the development and the progression or regression of retinopathy.
Results: Univariate analysis confirmed that four factors were significantly associated with the etiology and the progression or regression of diabetic retinopathy: age, duration of diabetes, mean longitudinal GHb levels (all at P < 0.01), and diastolic blood pressure (P < 0.04). However, age was no longer significant when controlled by duration of diabetes. Cigarette smoking was only associated significantly with background retinopathy (stages 2 and 3). Systolic blood pressure, sex, a family history of hypertension, and cholesterol levels were not significantly associated with retinopathy.
Conclusions: The onset of diabetic retinopathy is associated with the duration of diabetes, mean longitudinal GHb levels, smoking, and diastolic blood pressure. A longer duration of diabetes, higher GHb values, and higher diastolic blood pressure levels are associated with an increased risk of progression and a decreased chance of regression of diabetic retinopathy.