FDA approves Eli Lilly's once-weekly insulin efsitora alfa, branded Onswik

The US Food and Drug Administration has approved Onswik (insulin efsitora alfa-gobe), a once-weekly basal insulin injection for adults with type 2 diabetes, Eli Lilly announced on September 24, 2026 ^[3]. The drug is cleared as an addition to diet and exercise to improve blood sugar control, and is injected under the skin one time each week on the same day of the week ^[2].

Onswik is the second once-weekly insulin the FDA has approved for adults with type 2 diabetes ^[2]. Novo Nordisk's Awiqli was cleared in March and became the first weekly insulin available in the US, following two FDA rejections in 2024 over a requested type 1 diabetes indication and manufacturing concerns ^[1]. Novo refiled in September 2025 seeking a type 2 indication ^[1].

This is the fourth approval worldwide for Onswik, after regulatory clearances from the European Medicines Agency, Mexico's COFEPRIS and Japan's PMDA ^[3]. Lilly frames the appeal in simple arithmetic: weekly dosing is designed to cut more than 300 injections a year compared with a once-daily basal insulin ^[3].

One point of clarity for readers of this site: Onswik is an insulin, not a GLP-1 or GIP/GLP-1 medicine. It is not semaglutide (Ozempic, Wegovy, Rybelsus), tirzepatide (Mounjaro, Zepbound) or orforglipron (Foundayo). It works by replacing background insulin, and weight gain is listed among its common side effects ^[2][3].

What the trials showed

Approval rests on the QWINT Phase 3 program, which enrolled more than 3,400 adults with type 2 diabetes across four registration studies that began in 2022 ^[3]. The trials covered people who had never used insulin, people already on once- or twice-daily basal insulin, and people on both basal and mealtime insulin ^[2].

In each study, weekly Onswik met its primary endpoint of non-inferior A1C reduction compared with once-daily insulin glargine U-100 or insulin degludec U-100 ^[3]. The FDA's own summary says Onswik reduced hemoglobin A1c to a similar extent as those two daily comparators ^[2]. In QWINT-2, which randomized 928 insulin-naive adults, Onswik lowered A1C by 1.34% versus 1.26% for degludec ^[1][3]. QWINT-1 randomized 795 insulin-naive adults against glargine over 52 weeks; QWINT-3 randomized 986 adults already on basal insulin against degludec; QWINT-4 randomized 730 adults on basal plus mealtime insulin against glargine over 26 weeks ^[3].

Safety looked broadly similar to the daily basal insulins studied ^[3]. The most common adverse reactions are hypoglycemia, allergic reactions, injection site reactions, lipodystrophy, itching, rash, swelling and weight gain ^[2][3]. The label also carries warnings about medication errors and accidental overdose, hypersensitivity reactions, low potassium, and fluid retention and heart failure when used with certain medicines, including TZDs ^[2][3]. Severe hypoglycemia can cause seizures, unconsciousness, life-threatening complications or death ^[2].

Onswik is not recommended for people with type 1 diabetes because of an increased risk of severe hypoglycemia ^[2][3]. It has not been studied in children, and it is not known whether it is safe and effective in them ^[3].

Why it matters for patients

For adults with type 2 diabetes who take a daily basal insulin, weekly dosing changes the routine, not the disease. The trade-off is fewer injections against a dosing system that works differently from other insulin pens. Lilly's own labeling stresses that the Onswik KwikPen dials differently from other injectable diabetes medicines, comes in two concentrations — U-500 (500 units/mL) dialing in 5-unit increments, and U-1,000 (1,000 units/mL) dialing in 10-unit increments — and should not be diluted, mixed, used in a pump, or drawn into a syringe ^[3].

Missed doses have their own rules: the label says a missed dose can be taken within 4 days (96 hours), after which the dose is skipped or the weekly schedule is reset ^[3]. Because a weekly dose cannot be pulled back once injected, the practical questions about hypoglycemia management are conversations for a prescriber.

Many people take a basal insulin alongside a GLP-1 medicine. QWINT-2 was designed to look at efficacy and safety in participants using and not using GLP-1 receptor agonists, though specific results for those subgroups have not been detailed here ^[3].

What happens next

Lilly says the Onswik KwikPen will be available in the US "in the coming months" in both concentrations — 1,500 total units in the U-500 pen and 3,000 total units in the U-1,000 pen ^[1][3]. A US list price, launch date and insurance coverage terms have not been disclosed.