Once-a-Week Insulin Shows Promise in Clinical Trial

Insulin has long been a cornerstone of treatment for type 1 and 2 diabetes. Dominant manufacturers like Eli Lilly, Novo Nordisk, and Sanofi not only offer a range of insulin products but are also continuously innovating. Recently, Eli Lilly released promising results for its once-weekly insulin, efsitora alfa (efsitora), marking a significant advancement in diabetes management. 

In phase 3 clinical trials (the point in research when the safety of a treatment is tested) Lilly found that efsitora reduced A1C by 1.34% compared to 1.26% for insulin degludec. What’s more, participants taking efsitora spent 45 minutes more time in range and 37 more minutes in tight range compared to degludec, meaning that efsitora provided better glucose control.

Is Efsitora the First Once-Weekly Insulin?

Lilly’s results come shortly before the Food and Drug Administration’s Endocrinologic and Metabolic Drugs Advisory Committee meets to review the safety and efficacy of Novo Nordisk’s once-weekly insulin Awiqli (insulin icodec). If the FDA approves Awiqli, it will be the first once-weekly insulin available in the United States.

How Would Once-Weekly Treatment Work?

Kathleen Wyne, MD, PhD, the director of the adult type 1 diabetes program at the Ohio State University Wexner Medical Center, told Verywell that one of the potential benefits of once-weekly insulin is that it would require fewer injections overall. Instead of once- to twice-daily injections, patients would receive a single weekly injection.  

“We do know that many patients miss up to three to four doses of basal insulin a week,” said Wyne. “The weekly dosing would help to maintain consistent blood levels without missed doses, leading to improvements in time in range (TIR) and A1c."

The Downsides of Once-Weekly Insulin

Despite the positive implications of once-weekly insulin, endocrinologists do have some concerns about the treatment coming to market. 

Marc-Andre Cornier, MD, professor of medicine at the Medical University of South Carolina and director of the division of endocrinology, diabetes, and metabolic diseases, told Verywell that hypoglycemia is a possibility with high insulin dosages. 

Hypoglycemia, or low blood glucose, occurs when blood sugar levels drop excessively as a result of too much insulin in the body, underscoring the importance of continuous blood glucose monitoring. “For example, they [patients] accidentally give themselves too much that insulin is going to stay in their system a lot longer, so the effects of low blood glucose could be prolonged,” said Cornier.

Another potential drawback of once-weekly insulin is that it can be harder to adjust on a short-term basis. For example, if a patient needs to withhold meals or undergo a surgical procedure, managing insulin levels could be more challenging on a once-weekly dosing regimen.

If once-weekly insulins were to become available, Corner said that patients would still need to check their blood glucose regularly using a finger stick or sensor technologies that deliver continuous glucose monitoring. Their insulin would then need to be adjusted based on their blood glucose levels. 

“Typically, with once-a-day insulins, we’re adjusting that potentially every three to five days, depending on the insulin, or when patients come in for visits,” said Cornier. “With the once-a-week insulin, we need to learn how often we would be making those changes and how big of a change would we need to do.” 

According to Cornier, insulin manufacturing companies like Lilly and Novo Nordisk likely have existing protocols on insulin adjustments; however, he added it’s that providers might adopt those protocols and adjust them over time. 

Are There Currently Alternative Insulin Dosing Schedules Beyond Once a Day?

For the most part, all insulins on the market today are intended to be taken every day.

“Every other day has been tested with current long-acting insulins,” said Wyne. The biggest challenge? Since endocrinologists adopt a seven-day week for insulin, that would mean patients would not be dosing on the same days each week, potentially making insulin adherence more complicated. 

“The current insulins proposed as once weekly would not be appropriate to dose less frequently, even in low doses,” according to Wyne. 

Can Type 1 Diabetes Patients Use Once-Weekly Insulin? 

While Cornier doesn’t count type 1 diabetes patients out for once-weekly insulin, it might be difficult to pull off. “It could be an option for patients with type 1 diabetes, but I think the overall benefits will be more for people with type 2 diabetes where you don’t need necessarily to adjust things on a more rapid basis as you might with type 1,” said Cornier.

How Much Would Once-Weekly Insulin Cost?

Efsitora has not been approved in the U.S., so experts say it’s difficult to determine the price point as well as predict whether it would be more cost-effective than daily insulin. However, “as with any new medication, it will probably initially be expensive,” said Wyne.

Experts do agree that reducing injection frequency will make type 2 diabetes management more convenient for patients, so once-weekly insulin could become a powerful tool for improving disease management.