Long-term cumulative incidence of clinically diagnosed retinopathy in the Finnish Diabetes Prevention Study.

CONTEXT:Lifestyle intervention reduces the incidence of type 2 diabetes (T2D) in people with impaired glucose tolerance. OBJECTIVE:To find out whether participation in the earlier lifestyle intervention had an effect on the occurrence of clinically diagnosed retinopathy during a median of 22 years of follow-up time. METHODS:The study included 505 individuals from the Finnish Diabetes Prevention Study (DPS) (mean 55, range 40-64 years at the onset of the study) with impaired glucose tolerance who were originally randomized into the intervention (weight loss, healthy diet and physical activity (N=257) and usual care control groups (N=248). The median follow-up was 22 years. Clinical retinopathy diagnoses were obtained from the Finnish national hospital Care Register for Health. Data on glycemic parameters, serum lipids and blood pressure were available from both the intervention (median 4 years) and post-intervention period (until the year 7). RESULTS:No significant difference was found in the cumulative incidence of clinically diagnosed diabetic retinopathy between the original intervention (N=23, 8.9%) and control groups (N=19, 7.7%) during the extended follow-up (Odds ratio: 1.15, 95% confidence interval: 0.61-2.21). A higher cumulative HbA1c was significantly associated with a higher risk of retinopathy (Hazard ratio 1.4; 1.02-1.88, 95% posterior interval, adjusted for group, age and sex). Furthermore, the incidence of retinopathy diagnosis was numerically more common among individuals who had developed diabetes during the follow-up (33/349) compared with those who had not (9/156), however, the comparison was not statistically significant (Odds ratio: 1.86, 95% confidence interval: 0.89-4.28, adjusted for group, age and sex). CONCLUSION:A higher cumulative HbA1c was significantly associated with a higher risk of retinopathy. No evidence was found for a beneficial effect of a 4-year lifestyle intervention on the long-term occurrence of clinically diagnosed retinopathy during a median of 22-year follow-up.