Purpose: To explore whether insulin resistance and beta-cell dysfunction are both related to diabetic retinopathy (DR) in type II diabetics by using a community-based study in Kinmen, Taiwan.
Methods: A screening program for DR was performed by a panel of ophthalmologists who used ophthalmoscopy and 45 degrees color retinal photographs on dilated pupils to determine a consensus grade of diabetic retinopathy. Screening, which was conducted between 1999 and 2002, involved 971 patients diagnosed with type II diabetes. The Homeostatis Model Assessment (HOMA) method was used to determine insulin resistance and beta-cell dysfunction.
Results: Seven hundred twenty-five diabetics who attended ophthalmological fundus checkups were studied. The overall response rate was 75%. After excluding 10 insulin-treated diabetics, diabetic retinopathy at first eye screening among the remaining 715 diabetics was 18.5%. Based on the multiple logistic regression, DR was found to be strongly related to both baseline insulin resistance (IR) and beta-cell dysfunction regardless of duration of diabetes. The strength of the relationships was maintained after adjustment for confounders. Those who were in the 2nd, 3rd, and 4th quartile of HOMA IR had 1.38 times (95% CI: 0.62-3.05), 2.37 times (95% CI: 1.19-4.69), and 4.16 times (95% CI: 2.15-8.06) the risk for DR compared to that in the 1st quartile, respectively. A reduced risk for DR in relation to HOMA beta-cell dysfunction for the 2nd, 3rd, and 4th quartile were 64% (95% CI: 27%-82%), 82% (95% CI: 58%-92%), and 82% (95% CI: 60%-92%) compared to that in the 1st quartile, respectively.
Conclusions: Insulin resistance and beta-cell dysfunction are both associated with diabetic retinopathy in type II diabetes.