Ranibizumab, an intravitreally administered inhibitor of vascular endothelial growth factor (VEGF), is approved for the treatment of visual impairment associated with diabetic macular oedema (DME) in the EU. In four well designed, phase II or III trials (RESOLVE, RESTORE, RIDE and RISE), 1-2 years' treatment with ranibizumab was more effective than sham or focal/grid laser therapy in improving best corrected visual acuity (BCVA) and reducing central retinal thickness (CRT) in patients with visual impairment associated with DME. Additionally, in two well designed phase III trials (RESTORE and DRCR.net-1), 1 year of treatment with ranibizumab as an adjunct to laser therapy was more effective than laser monotherapy in improving BCVA and CRT in patients with visual impairment associated with DME. Improvements in BCVA with ranibizumab alone or as an adjunct to laser therapy were observed at the first follow-up visits in these studies (i.e. 1-4 weeks after the start of treatment), and were associated with gains in vision-related quality of life, as assessed using the National Eye Institute Visual Functioning Questionnaire-25. The ocular and non-ocular adverse event profile of ranibizumab in patients with DME is similar to that observed in patients with neovascular (wet) age-related macular degeneration or retinal vein occlusion. Based on tolerability data from clinical trials, there is no indication that ranibizumab alone or combined with laser is associated with an increased risk of cardiovascular or cerebrovascular events potentially related to systemic VEGF inhibition.