Tirzepatide in type 1 diabetes: beyond mere weight loss.

This narrative review examined the clinical potential of tirzepatide — a dual agonist of the GLP-1 receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) — specifically in type 1 diabetes mellitus (T1DM), a population distinct from the type 2 diabetes and obesity contexts in which tirzepatide is already established. Researchers searched PubMed/MEDLINE, Scopus, and Google Scholar through March 2026. Across the reviewed studies, tirzepatide was associated with reductions in HbA1c of up to 0.9%, body weight reductions of up to 23.4% (up to 9.0 kg/m² BMI reduction), increases in continuous glucose monitoring time-in-range (TIR) of up to 18.0% (primarily driven by reductions in time above range), and decreases in daily insulin requirements of up to 38 units/day. The authors noted that glycemic and weight benefits appeared to be partly, but not exclusively, mediated by weight loss. Key limitations acknowledged include that most available studies are observational in design, enrolled participants with overweight or obesity, and that randomized controlled trials in T1DM populations are still needed to confirm these findings.

Why this grade: As a narrative review synthesizing predominantly observational human studies in T1DM, the evidence base is limited by the lack of randomized controlled trials and the inclusion of mostly overweight/obese populations, precluding broad generalization.