Even with optimal glycaemic control, individuals with type 1 diabetes (T1DM) continue to face elevated risks of cardiovascular disease (CVD). One key contributor is insulin resistance (IR), often driven by high doses of exogenous insulin. Unlike natural insulin, which is released by the pancreas and largely broken down by the liver before entering circulation, injected insulin bypasses this filtration, leading to supra-physiological levels. Over time, this can promote IR and contribute to weight gain, PCOS, MASLD and other metabolic disturbances.
Insulin pumps can help mitigate these effects, with average dose reductions of 10–15% compared to multiple daily injections. Clinically, IR is often defined as a requirement for insulin doses exceeding 1.2–1.5 units/kg/day.
IR is closely linked to endothelial dysfunction—a state where the cells lining our blood vessels lose their flexibility and protective functions. This can result in increased arterial stiffness, reduced nitric oxide production, and a greater tendency toward clot formation.
GLP-1 receptor agonists such as Semaglutide (Ozempic) have shown promise in improving IR in type 2 diabetes and obesity. These medications have demonstrated benefits in reducing cardiovascular events, stroke, and kidney disease. Recent research is now exploring their role in T1DM. Although powered studies are limited due to the smaller T1DM population, early data is encouraging. For instance, a recent NEJM study involving people with T1DM on insulin pumps and BMI >30 found that over 26 weeks, 36% of participants on Semaglutide achieved >5% weight loss, >70% time in range, and <4% hypoglycaemia. None in the placebo group met these criteria—and importantly, there were no cases of diabetic ketoacidosis (DKA).
Currently, GLP-1 medications such as Semaglutide and Tirzepatide are not PBS-funded in Australia or covered by insurance in the US for T1DM, pending more robust cardiovascular outcomes data. However, in Australia, these therapies remain relatively affordable for private patients.
While not suitable for every person with T1DM, for those with additional CVD risk factors, GLP-1 medications may offer meaningful metabolic and vascular benefits. For patients facing cost barriers, clinical trials remain a great option—and sites such as St Vincent’s Hospital in Sydney are actively recruiting.