Despite research efforts in the past 20 years, scientific evidence about screening and treatment for depression in diabetes remains incomplete and is mostly focused on North American and European health-care systems. Validated instruments to detect depression in diabetes, although widely available, only become effective and thus recommended if subsequent treatment pathways are accessible, which is often not the case. Because of the well known adverse effects of the interaction between depression and diabetes, treatment goals should focus on the remission or improvement of depression as well as improvement in glycaemic control as a marker for subsequent diabetes outcome. Scientific evidence evaluating treatment for depression in type 1 and type 2 diabetes shows that depression can be treated with moderate success by various psychological and pharmacological interventions, which are often implemented through collaborative care and stepped-care approaches. The evidence for improved glycaemic control in the treatment of depression by use of selective serotonin reuptake inhibitors or psychological approaches is conflicting; only some analyses show small to moderate improvements in glycaemic control. More research is needed to evaluate treatment of different depression subtypes in people with diabetes, the cost-effectiveness of treatments, the use of health-care resources, the need to account for cultural differences and different health-care systems, and new treatment and prevention approaches.