Anaemia and diabetes have a multifaceted relationship. Their co-existence contributes to each other's etiopathogenesis, natural history, clinical presentation and prognosis. Anaemia may occur in autoimmune disease that coexists with type 1 diabetes, in erythropoietin deficient and in erythropoietin hyporesponsive states. Iron deficiency, haemolytic and megaloblastic anaemia occur in diabetes through various mechanisms. Anaemia is associated with, and contributes to, worsening of both microvascular and macrovascular complications. Altered red blood cell physiology may influence results of glycated haemoglobin. While certain glucose-lowering drugs and antihypertensive drugs may cause iatrogenic anaemia, others help in improving blood health. This review synthesizes all these relationships, and their underlying mechanisms, in a simple, reader-friendly format. This information should help the diabetes care professional to practice due rubrivigilance, i.e. keep a high index of clinical suspicion for anaemia in diabetes care.