Risk factors for the development of diabetic retinopathy in Japanese type 2 diabetic patients

This study investigated the risk factors for development of diabetic retinopathy (DR) in 787 type 2 diabetic patients with no retinopathy at the first visit. The subjects were followed up for at least 3 years (mean, 6.7 years). Among the baseline factors, significant correlations were observed between the development of DR and HbA1c (P < 0.0001), the method of therapy (P < 0.005), the duration of diabetes at the first visit (P < 0.005) and the past maximal body mass index (BMI) (P < 0.01). No significant correlation was found with the blood pressure, age, gender, TC or BMI. Among the follow-up variables, the mean HbA1c (P < 0.0001) and duration of diabetes (P < 0.001) correlated significantly with DR development, whereas the blood pressure and age did not. We found that a 1% decrease in HbA1c led to a 35% reduction in the risk of development of DR during the follow-up. The patients whose HbA1c at the first visit was higher than the median value of 8.2% showed a higher probability of development of DR during the next 3 years even when the same blood glucose control was maintained during the follow-up. In conclusion, our study demonstrated that the most important risk factor influencing the development of DR was the blood glucose control. Moreover, we found that the glycemic level at the first visit also influenced the development of DR.