The drugs semaglutide (marketed as Ozempic and Wegovy) and tirzepatide (marketed as Mounjaro and Zepbound) are widely used to treat people with type 2 diabetes. Many large, well-done research studies of thousands of people have clearly shown that these drugs can improve glucose control, reduce the need for other glucose lowering drugs, and promote weight loss. Theses studies also showed that these drugs lower the future risk of serious health problems such as heart attacks, strokes, heart failure, kidney disease, and other diseases. Because of this large body of research, the companies that manufacture these drugs received approval from Health Canada to market them for the treatment of type 2 diabetes as well as obesity.
The effects of these drugs in people with type 1 diabetes is less well understood. This is because very few completed studies included people with type 1 diabetes, and the ones that did include them were small. Because of this, no company has submitted these data to Health Canada or other regulatory agencies. As a result, no regulatory authority in the world has approved the use of these drugs for the treatment of type 1 diabetes. Nevertheless, the studies that did focus on type 1 diabetes reported that these drugs can modestly improve glucose control and promote some weight loss and have side effects like those observed in type 2 diabetes. The effect of these drugs on heart disease and other long-term consequences is totally unknown.
What all of this means is that the prescription of these drugs to someone with type 1 diabetes is considered “off-label”. In other words, the official label that guides the prescription of these dugs states that it is not approved for use in people with type 1 diabetes. Healthcare providers who prescribe it therefore need to inform the patient that it is off-label use. They also need to have an open and clear discussion in which they describe the limitations of the data that are available regarding the drug and what is known about its use and side effects in type 1 diabetes based on this research.
The side effects experienced by people with type 1 diabetes include the weight loss and nausea (and rarely vomiting) that can affect people with type 2 diabetes. In addition, they often need to reduce the amount of insulin needed to avoid having low blood sugar reactions (hypoglycemia). It is extremely important that every person with type 1 diabetes understand that they should never stop their insulin completely, because doing that would put them at risk for life threatening ketoacidosis.
In summary, healthcare providers are increasingly using drugs like semaglutide and tirzepatide “off-label” in people with type 1 diabetes who are also overweight or obese. Ongoing studies will hopefully provide enough reassuring data to support approval of one of these drugs so that it can be used more widely. In the meantime, cautious use, particularly with continuous glucose monitoring, appears to help some patients. As with everything, the advice and guidance of an experienced diabetes healthcare professional can make all the difference.
About the author
Hertzel Gerstein
Hertzel is an endocrinologist and professor at McMaster University who is in high demand as a speaker, advocate, and educator on diabetes-related topics. His research focuses on using large, international randomized trials to identify and test new ways of preventing type 2 diabetes, reducing serious health outcomes like strokes and death, and achieving type 2 diabetes remissions.
