Diabetes mellitus Type 1 is one of the most common diseases in childhood. Severe, secondary diseases like hypertension or blindness are results of micro- and macrovascular complications caused by insufficient glycaemic control. Especially adolescent patients with type 1 diabetes have a lower adherence rate. The DIADEMA trial proved that community pharmacist in collaboration with diabetologists and diabetes advisors can have a positive impact on the therapy of adolescents with type 1 diabetes. This article highlights and explains which components of the pharmacist intervention caused the preferable adjustments and improved the insulin therapy of the patients.