Metabolic Benefits vs. Cardiovascular Uncertainty: A Critical Review of GLP-1 Receptor Agonists in Type 1 Diabetes

Type 1 diabetes (T1DM) is associated with elevated cardiovascular (CV) risk, often exacerbated by the rising prevalence of obesity. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) reduce CV risk in type 2 diabetes, but their role in T1DM is less well-defined. This umbrella review synthesizes evidence from systematic reviews, meta-analyses, and Mendelian Randomization (MR) studies to evaluate the metabolic efficacy and safety of GLP-1 RAs in T1DM. Adjunctive therapy, particularly with liraglutide and exenatide, was associated with clinically meaningful weight reduction (mean difference: -4.35 kg to -5.1 kg) and lower total daily insulin doses. HbA1c reductions were statistically significant but modest (0.2-0.3%), with no improvement in Time in Range. Secondary benefits included lower systolic blood pressure. Safety data were mixed: the risk of severe hypoglycemia was not increased, whereas Time Below Range and gastrointestinal adverse events were more frequent. Evidence on diabetic ketoacidosis (DKA) was inconsistent across studies. Overall, GLP-1 RAs improve weight and reduce insulin requirements in T1DM, potentially mitigating indirect CV risk factors; however their direct cardiovascular benefits remain unproven in the absence of dedicated outcome trials.