The number of patients with diabetes mellitus will increase over the coming years, so that there will also be more patients with diabetic macular oedema. Diabetic macular oedema and diabetic retinopathy are the most important causes of legal blindness in adults. The current therapy of diabetic macular oedema consists of the prevention, detection and treatment of risk factors (e.g., hypertension, hyperglycaemia, dyslipidaemia, proteinuria and obesity), complemented if necessary by photocoagulation therapy. Photocoagulation therapy may prevent or reduce vision loss in many patients, but usually does not improve visual acuity. New treatment strategies include intravitreal corticosteroids or vascular endothelial growth factor (VEGF) inhibitors, and oral protein kinase C inhibitors, angiotensin converting enzyme (ACE) inhibitors, acetylsalicylic acid or statins. The long-term positive effect of these strategies is controversial and the side effects can be serious.