To specify the risk factors for pseudophakic cystoid macular edema (CME) in patients with diabetes. Kymenlaakso Central Hospital, Unit of Ophthalmology, Kotka, Finland. Prospective case series. Patients with type 1 or type 2 diabetes having routine cataract surgery were evaluated. Spectral-domain optical coherence tomography imaging was performed before surgery and 1month postoperatively. The study comprised 93 patients (95 eyes). The central retinal thickness increase was 9.7μm±1.7 (SEM) in diabetic patients with no retinopathy, 22.7±8.6μm in those who had nonproliferative retinopathy, and 73.8±37.4μm in those who had proliferative retinopathy (P<.001). The central retinal thickness increase was greater in the eyes of diabetic patients with insulin dependence than in eyes of patients using noninsulin medication (21.9±5.9μm versus 8.3±1.8μm, P=.017). Serum hemoglobin A1c concentration and inversely, patient age, were associated with central retinal thickness increase, even after adjustment for confounding factors (r=0.607, P<.001 and r=0.417, P=.001, respectively). The central retinal thickness change was smaller in the eyes of patients who had a nonsteroidal antiinflammatory drug (NSAID) as their postoperative antiinflammatory medication than in eyes of patients who were not prescribed NSAID medication when retinopathy was analyzed as a covariant (8.2±3.6μm versus 13.6±2.9μm, P=.016). Young patient age and poor glycemic control were risk factors for postoperative central retinal thickness increase. This study showed it is necessary to identify, effectively treat, and follow-up with patients with diabetes who are at a greater risk for pseudophakic CME.