Diabetes mellitus may occur in children and adolescents as an independent disease, most frequently as autoimmune type 1 diabetes, or can coexist with other abnormalities. If diabetes coincides with other disorders occurring sequentially, a syndromic form of monogenic diabetes should be suspected. Thiamine-responsive megaloblastic anaemia (TRMA) syndrome is an example of a rare form of monogenic diabetes coexisting with anaemia and deafness. In the paper, we discuss clinical features and treatment of TRMA syndrome - a unique syndromic form of vitamin-dependent monogenic diabetes. The review might be useful in establishing a prompt diagnosis and initiating optimal management in children and adolescents with the disease.