Nowadays, diabetes mellitus is an important public health problem. Together, population growth, prevalence of obesity, and a sedentary lifestyle has led to an increased number of individuals with diabetes mellitus. Globally, cataracts remain the leading cause of blindness and the second cause of visual impairment among patients with diabetes mellitus. Phacoemulsification with intraocular lens implantation is the standardised surgical technique to treat cataracts. Advances in cataract surgical techniques have significantly decreased the incidence of complications. However, surgery may not be safe, as the risk of complications increases in patients with diabetes mellitus with pre-existing blood-ocular barrier pathology. Cystoid macular oedema is one of the most severe postoperative complications after cataract surgery. It is considered the most important cause of suboptimal visual acuity and strongly affects early recovery. The optimal pharmacological therapy for prevention of CME following cataract surgery in patients with diabetes mellitus continues to be debated and needs further investigation. © Russian Association of Endocrinologists, 2017.