The incidences of and risk factors for severe retinopathy requiring photocoagulation and albuminuria in Japanese patients with childhood-onset type 1 diabetes

The aim of this study was to clarify the incidences of and the risk factors for severe retinopathy requiring photocoagulation therapy and albuminuria in Japanese patients with childhood-onset type 1 diabetes mellitus. A total of 756 patients from a cohort study by the Japanese Study Group of Insulin Therapy for Childhood and Adolescent Diabetes were included in the study. Patients were registered in 1995 or 2000, and HbA_1cwas measured every 4 months and analyzed in central hospital for an average of 6 years. The presence of severe retinopathy requiring laser photocoagulation and the presence of albuminuria was checked for during the period 2010-2011. During a median of 18 (range: 15-21) years, 34 out of 756 patients underwent laser photocoagulation and 57 out of 605 patients developed albuminuria. A Cox proportional hazards model showed that the risk of severe retinopathy requiring laser photocoagulation increased by 1.15 (95% confidence interval [CI] 1.03-1.29, p = 0.012) with each increase of a year in the age at onset, by 4.03 (95% CI 1.20-13.5, p = 0.024) in females, and by 2.05 (95% CI 1.69-2.49, p < 0.0001) with each increase of 1% in HbA_1c. The risk of albuminuria increased significantly, by 1.09 (95% CI 1.01-1.18 p = 0.037), with each increase of a year in the age at onset and by 2.38 (95% CI 1.93-2.97 p < 0.0001) with each increase of 1% in HbA_1c. In Japanese patients with childhood-onset type 1 diabetes, older age at the onset of diabetes, female rather than male gender, and higher HbA_1c were found to increase the risk of requiring photocoagulation. No patients with HbA_1c < 7.5% developed severe retinopathy requiring photocoagulation therapy. The risk of developing albuminuria increased with age at onset of diabetes and HbA_1c. Female gender was a strong risk factor for severe retinopathy requiring photocoagulation, but not for albuminuria.