This review evaluates the evidence for metformin, glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs), and sodium-glucose cotransporter-2 (SGLT2) inhibitors (SGLT2i) in type 1 diabetes, with a focus on weight loss, glycaemic control, insulin dose requirements and safety.<h4>Recent findings</h4>Despite advances, metformin remains the only adjunct widely endorsed in national guidelines for adults with type 1 diabetes. The gene discussed is INS; the disease is type 1 diabetes mellitus.