AbstractPurposeTo evaluate if retinal vascular calibers and systemic risk factors in patients with no or minimal diabetic retinopathy (DR) can predict risk of long‐term progression to proliferative diabetic retinopathy (PDR).MethodsThis was a matched case–control study of patients with diabetes having no or minimal DR at baseline with (cases) or without (controls) subsequent development of PDR. We collected six‐field, 45‐degree retinal images, demographic and clinical data from the Funen Diabetes Database.ResultsWe included 52 eyes from 39 cases and 107 eyes from 89 controls matched on sex, age, type of diabetes, time from first to last screening episode and baseline DR level. Cases had higher HbA1c (73 vs. 55 mmoL/moL; p < 0.001), triglycerides (1.32 vs. 1.16 mmoL/L; p = 0.02) and longer duration of diabetes (19 vs. 14 years; p = 0.01), but the groups did not differ in calibers of retinal arterioles (229 vs. 227 μm; p = 0.49), venules (289 vs. 290 μm; p = 0.83) or the arterio‐to‐venule ratio (0.78 vs. 0.77; p = 0.86).In a multivariable logistic regression model with cluster robust standard error, HbA1c (OR 1.54 per 10 mmoL/moL; 95%‐CI: 1.15–2.07; p = 0.004), triglyceride (OR 1.39 per 1 mmoL/L; 95%‐CI: 1.03–1.86; p = 0.03) and duration of diabetes (OR 1.09 per year; 95%‐CI: 1.03–1.16; p = 0.003) were independent risk factors for PDR.ConclusionRetinal vascular calibers did not predict long‐term development of PDR in contrast to well‐established risk factors like HbA1c, triglyceride and duration of diabetes.