Objective: To examine the association between retinal vascular geometry and subsequent development of incident retinopathy in young patients with type 1 diabetes.
Research design and methods: A prospective cohort study of 736 people with type 1 diabetes aged 12 to 20 years, retinopathy-free at baseline, attending an Australian tertiary care hospital. Retinopathy was determined from seven-field retinal photographs according to the modified Airlie House Classification. Retinal vascular geometry, including length/diameter ratio (LDR) and simple tortuosity (ST), was quantified in baseline retinal photographs. Generalized estimating equations were used to determine risk of retinopathy associated with baseline LDR and ST, adjusting for other factors.
Results: After a median 3.8 (interquartile range 2.4-6.1) years of follow-up, incident retinopathy developed in 287 of 736 (39%). In multivariate analysis, lower arteriolar LDR (odds ratio 1.8 [95% CI 1.2-2.6]; 1st vs. 4th quartile) and greater arteriolar ST (1.5 [1.0-2.2]; 4th vs. 1st quartile) predicted incident retinopathy after adjusting for diabetes duration, sex, A1C, blood pressure, total cholesterol, and BMI. In subgroup analysis by sex, LDR predicted incident retinopathy in male and female participants (2.1 [1.1-4.0] and 1.7 [1.1-2.7]; 1st vs. 4th quartiles, respectively) and greater arteriolar ST predicted incident retinopathy in male participants (2.4 [1.1-4.4]; 4th vs. 1st quartile) only.
Conclusions: Lower arteriolar LDR and greater ST were independently associated with incident retinopathy in young people with type 1 diabetes. These vascular geometry measures may serve as risk markers for diabetic retinopathy and provide insights into the early structural changes in diabetic microvascular complications.