Published 25 October 2026
The missing piece in type 1 diabetes management
For 34 years I have lived with type 1 diabetes, and I know from experience that insulin alone is not enough. Intensive insulin therapy keeps us alive, but it also drives weight gain, insulin resistance, and a cycle of rising doses that is hard to break. Now a class of drugs developed for type 2 diabetes is offering a way out.
GLP-1 receptor agonists, commonly known as GLP-1s, are not approved for type 1 diabetes. The FDA has not given them an indication for this population, and current diabetes guidelines do not recommend them as routine therapy. Yet real-world data and clinical trials are building a compelling case for their off-label use as an adjunct to insulin, particularly for people who are overweight or obese and struggling to meet their glycemic targets.
What the evidence shows
A 2023 meta-analysis of 24 studies involving more than 3,000 people with type 1 diabetes found that adding a GLP-1 receptor agonist to insulin therapy produced meaningful metabolic benefits. Participants lost an average of 3.5 to 5 kg, reduced their HbA1c by 0.2 to 0.3 percent, and cut their total daily insulin dose by about 5 to 7.5 units. These were not small studies, and the effect was consistent across different agents.
Newer agents are showing even stronger results. The ADJUST-T1D trial of semaglutide, a once-weekly GLP-1, reported a 5.3 kg weight loss and an 11.3 unit-per-day reduction in insulin use over 26 weeks. A 12-month real-world study found semaglutide users with type 1 diabetes lost nearly 9 kg and reduced their insulin doses by more than 8 units per day compared with matched controls. Tirzepatide, a dual GIP and GLP-1 receptor agonist, is producing weight reductions of around 11 kg and insulin dose reductions of 11 to 23 units per day in observational studies.
How it works
GLP-1s tackle the metabolic problems that insulin alone cannot. They suppress the inappropriate glucagon surge that happens after meals in people with type 1 diabetes, slow gastric emptying, and act on the brain to reduce appetite and carbohydrate intake. The result is lower postprandial glucose, reduced insulin needs, and weight loss. In people using automated insulin delivery systems, the combination is especially promising because the system can adjust to the lower insulin requirements and reduce hypoglycemia risk in real time.
The safety picture
This is where caution matters. The largest trials in type 1 diabetes, the ADJUNCT ONE and TWO studies of liraglutide, showed increased rates of symptomatic hypoglycemia and ketosis. Gastrointestinal side effects, especially nausea and vomiting, are common and drive discontinuation in some patients. However, more recent real-world and AID-combination studies have not shown a significant increase in severe hypoglycemia or diabetic ketoacidosis. A 2024 safety meta-analysis concluded that severe hypoglycemia was not increased, though time below range on CGM did rise slightly.
The 2025 Diabetes Technology Society consensus report, convened by leading endocrinologists and engineers, concluded that GLP-1 receptor agonists have the potential to improve glycemic and metabolic outcomes in adults with type 1 diabetes using automated insulin delivery, without increasing the risk of severe hypoglycemia or DKA, provided insulin doses are carefully adjusted.
Who should consider it
The evidence points to a specific group: adults with type 1 diabetes who are overweight or obese, have insulin resistance, or cannot achieve glycemic targets despite intensive therapy. If you are at a healthy weight, the risks likely outweigh the benefits. If you have gastroparesis, these drugs are contraindicated. If you are pregnant or planning pregnancy, they are not appropriate.
For those who do meet the criteria, the practical steps are clear. Start low, go slow, and adjust insulin before the first dose. Clinical practice guidelines suggest reducing bolus insulin by around 20 percent and basal insulin by 10 percent when initiating therapy, then fine-tuning based on CGM data. Watch for ketones during illness or prolonged fasting, and keep rapid-acting carbohydrate on hand for the rare but real risk of hypoglycemia in the first few weeks.
The missing middle
What remains unproven is whether GLP-1s reduce heart attacks and strokes in type 1 diabetes. We know they do in type 2 diabetes, but the cardiovascular outcome trials have not included type 1 populations. We also do not have long-term data on bone health, retinopathy, or kidney outcomes in type 1 diabetes. These are not reasons to dismiss the therapy, but they are reasons to demand proper trials and to monitor closely.
GLP-1 receptor agonists are not a replacement for insulin. They are a bridge out of the weight gain and insulin resistance cycle that makes type 1 diabetes harder to manage over time. Used carefully, they can be that bridge. Used carelessly, they are just another side effect waiting to happen.
Sources
Shah VN et al. Consensus Report on GLP-1 Receptor Agonists as Adjunctive Treatment for Individuals With Type 1 Diabetes Using an Automated Insulin Delivery System. J Diabetes Sci Technol. 2024;19(1):191-216. doi:10.1177/19322968241291512
Park J et al. Glucagon-like peptide 1 analogues as adjunctive therapy for patients with type 1 diabetes: an updated systematic review and meta-analysis. J Clin Endocrinol Metab. 2023;109(1):279-292. doi:10.1210/clinem/dgad471
Wójcik-Sosnowska E et al. Metabolic Benefits vs. Cardiovascular Uncertainty: A Critical Review of GLP-1 Receptor Agonists in Type 1 Diabetes. Int J Mol Sci. 2026;27(9):3882. doi:10.3390/ijms27093882
Garg SK et al. Efficacy and safety of tirzepatide in overweight and obese adult patients with type 1 diabetes. Diabetes Technol Ther. 2024;26(6):367-374. doi:10.1089/dia.2024.0050
American Diabetes Association / European Association for the Study of Diabetes. The management of type 1 diabetes in adults. 2026 consensus report. Diabetologia. 2026. doi:10.1007/s00125-026-06833-z
Related Reading
Smart Diabetes Living – Practical guides for living well with type 1 diabetes.
Diabetes Australia – Support, resources, and advocacy for people with diabetes.
How this analysis is researched, sourced and corrected: Editorial standards and corrections. Spotted an error? Contact Philip Hall.
