Patients with type 1 diabetes mellitus (T1DM) traditionally had a low body mass index and microangiopathic complications were common. The Diabetes Control and Complications Trial, published in 1993, demonstrated that therapy aimed at maintaining HbA1c levels as close to normal as feasible reduced the incidence of microangiopathy. Since then, the use of intensive insulin therapy to optimise metabolic control became generalised, with two main side effects: a higher rate of severe hypoglycaemia and increased weight gain. Approximately 50% of patients with T1DM are currently obese or overweight, which reduces or nullifies the benefits of good metabolic control, and which has other negative consequences; therefore, strategies to achieve weight control in patients with T1DM are necessary. At present, treatment with GLP-1 and SGLT-2 inhibitors has yielded promising short-term results that need to be confirmed in studies with larger numbers of patients and long-term follow-up. It is possible that, in coming years, the applicability of bariatric surgery in obese patients with T1DM will be similar to that of the general population or T2DM.