To investigate long-term functional and anatomical outcomes, discontinuation patterns, drug switching and rates of nonimprovement in patients treated with ranibizumab pro re nata (PRN) regimen for diabetic macular oedema (DME) according to the Danish national guidelines. Retrospective cohort study of 566 eyes in 566 patients with centre-involved DME who started intravitreal treatment with ranibizumab between January 2011 and December 2013 in the Greater Copenhagen region. Data were retrieved from a database and patient records between January 2011 and March 2016 and analysed using mixed-model statistics. At the conclusion of follow-up, 24.6% were in active ranibizumab follow-up, 25.4% had switched to other intravitreal pharmacotherapy, 31.6% had been discontinued because of disease stability, 13.8% had been lost to follow-up, 1.4% had been discontinued because of low visual acuity (VA), and 3.2% had died. At baseline, mean best-corrected visual acuity (BCVA) and mean central subfield thickness (CST) were 64.9 (±15.0) letters and 400.2 (±120.3)μm. Mean change in BCVA and mean change in CST from baseline to 3, 12, 24, 36 and 48months of follow-up were +3.9, +3.5, +2.7, +1.8, +2.3 letters and -97.4, -102.6, -106.9, -105.9, -131.6μm, respectively. Mean number of injections was 6.1 in year 1 and 1.8 in year 4. In 93 patients, drug switching to aflibercept showed no difference between the two drugs on BCVA or CST. In 79 patients, CST decreased <10% compared to baseline during the first year. In a single-centre clinical setting, 566 patients treated for DME with ranibizumab according to the Danish national guidelines were followed for up to 4years. Best-corrected visual acuity (BCVA) outcomes are in the low end of clinical studies, but studied on a wider population and achieved with fewer injections.