Abstract
For many people with type 1 diabetes optimizing glucose control is very demanding, and often leads to risk of hypoglycaemia and weight gain and more than half of people with type 1 diabetes are overweight or obese. Glucagon-like peptide-1 (GLP-1) based pharmacotherapy is established as treatment of people with type 2 diabetes and obesity but are not recommended for treatment of type 1 diabetes. GLP-1 based pharmacotherapy has also beneficial effects on cardiovascular and kidney disease, which also are complications to type 1 diabetes. Prescription of GLP-1 based pharmacotherapy has become increasing popular as add-on treatment to insulin in type 1 diabetes. The most potent GLP-1 receptor agonist semaglutide and the dual GLP-1/glucose-dependent insulinotropic peptide tirzepatide have been investigated in small trials, primarily retrospective chart reviews in type 1 diabetes. The present narrative review assesses up to August 2025 the efficacy and safety of semaglutide and tirzepatide on glycaemic control, body weight, dose of insulin and adverse events. Two small, randomized trial has been published with semaglutid reporting weight loss of 5.3 kg and 9.2 kg, reduction of daily dose of insulin up to 30%. The reduction in HbA1c was about - 0.3% to - 0.5% with increased continuous glucose monitoring (CGM) time in range. With tirzepatide the weight loss has been between 10-20 kg and with major reduction (up to> 30%) in dose of insulin combined with small reduction in HbA1c but with increased CGM time in range. Hypoglycaemia and ketoacidosis have not been a problem in the studies with semaglutide and tirzepatide. The effect of semaglutide and tirzepatide on risk of cardiovascular and kidney disease in people with type 1 diabetes has not been investigated. Major, long-term, randomized, placebo-controlled trials to define the place of GLP-1 based pharmacotherapy in the treatment algorithm of people with different phenotypes of type 1 diabetes are warranted.