Type 1 diabetes is not a disease of too much insulin resistance. It is a disease of no insulin at all. So a drug that works by prodding the pancreas and slowing the stomach has never had an obvious place in it. Obesity in people with type 1, though, is common and rising. Somebody ran the trial.
What the trial did
Seventy-two adults with type 1 diabetes and a BMI of 30 or higher were randomized 1:1 to once-weekly semaglutide up to 1 mg, or placebo, for 26 weeks, double-blind. [1] Every participant was using an automated insulin delivery system — a pump and a continuous glucose monitor talking to each other. The primary endpoint was a composite, and it was strict: more than 70% of time between 70 and 180 mg/dl, less than 4% of time below 70, and at least 5% weight loss. All three, or you did not count.
What it found
36% of the semaglutide group hit all three. Zero percent of the placebo group did. The between-group difference was 36 percentage points, 95% CI 20.6 to 52.2, with P<0.001. A zero in a control arm is unusual and it reflects how demanding the composite was. How an endpoint is built decides what its headline can claim, which is also true of a combination result whose own comparator arm went unreported.
The components moved in the expected directions and by modest amounts. Glycated hemoglobin fell 0.3 percentage points more than placebo, 95% CI −0.6 to −0.05. Time in range rose 8.8 percentage points, 95% CI 3.9 to 13.7. Body weight fell 8.8 kg more than placebo, 95% CI −10.6 to −7.0. The weight number is the largest effect here by some distance, and it is the one the drug is already approved to produce.
The safety line
Two severe hypoglycemia events occurred in each group. No diabetic ketoacidosis was reported in either. Both of those are reassuring and neither is a clearance. Seventy-two people over 26 weeks cannot rule out an event that happens once in a few hundred patient-years, and DKA on a GLP-1 in type 1 diabetes is exactly the kind of event that would sit in that range.
What the trial cost before the drug
This is where the result gets expensive in a way the abstract does not mention. The comparator was not nothing. It was an automated insulin delivery system, which every participant already had. A pump and a CGM run to thousands of dollars a year before anybody buys a vial.
So the honest reading is narrow. In people with type 1 diabetes and obesity who are already on a closed-loop system, adding semaglutide improved a composite of glucose control and weight over 26 weeks. It says nothing about somebody managing type 1 on injections and fingersticks. That reader was not in the trial.
The drug itself is the smaller line item, which is the unusual part. Sellers on this roster publish a median of $179 a month for the injection, read September 2026, and you can put that against a year in the cost tool. It is a fraction of what the equipment costs. It is also the part no insurer is obliged to cover for an unapproved indication, and coverage is already the hard part for the approved ones.
The dose is low
One more thing to notice. The trial went up to 1 mg. Weight-loss prescriptions commonly climb well past that, and the dose people settle at is its own question. A 1 mg result does not transfer upward on its own. Neither does the safety record that came with it.
The trial was funded by Breakthrough T1D, a research foundation rather than a manufacturer. That is worth knowing in a field where it is often the other way round.