Background To estimate the 10-year incidence of referable diabetic retinopathy (DR) in a French population with type 1 and 2 diabetes mellitus (DM). A secondary objective was the assessment of safe screening intervals in patients with diabetes without retinopathy.

Methods Observational, prospective and multicentric study between June 2004 and September 2017 based on a regional screening programme for DR in the Paris region. The incidence of referable DR in patients without retinopathy at baseline was calculated by the Turnbull survival estimator. A safe screening interval was defined as a 95% probability of remaining without referable DR.

Results Among the 25 745 participants with type 1 (n=6086) or type 2 (n=19 659) DM, the 10-year cumulative incidence of referable DR was 19.10% (95% CI 17.21% to 21.14%) and 17.03% (15.78% to 18.35%), median (IQR) follow-up=3.33 (4.24) years. The safe screening interval for patients without DR at the first examination for type 1 and 2 DM was 2.2 (95% CI 2.0 to 2.4) and 3.0 (2.9 to 3.1) years, respectively. In a subgroup of low-risk patients with type 2 DM, the safe screening interval was 4.2 (3.8 to 4.6) years.

Conclusions These data suggest that in Paris area, a 2-year, 3-year and 4-year screening interval was considered safe for type 1 DM, type 2 DM and for low-risk patients with type 2 DM, respectively, without DR at the first examination. While these data might be used to support the consideration of extending screening intervals, a randomised clinical trial would be suitable to confirm the safety for patients with DM.