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January 06, 2026
3 min read
Key takeaways:
- Adults receiving once-weekly semaglutide 1 mg had a decline in total daily insulin dose at 4 weeks that was sustained at 26 weeks.
- Semaglutide was linked to fewer user-initiated boluses at all follow-ups.
Once-weekly semaglutide 1 mg was tied to a reduction in total daily insulin dose among adults with type 1 diabetes, researchers reported in a post hoc analysis of the ADJUST-T1D trial published in Diabetes Care.
As Healio previously reported, the ADJUST-T1D trial included 72 adults with type 1 diabetes using an automated insulin delivery system randomly assigned once-weekly injectable semaglutide 1 mg (Ozempic, Novo Nordisk) or placebo for 26 weeks. In the trial, 36% of the semaglutide group were able to achieve a CGM-measured time in range of at least 70%, a time below range of less than 4% and weight loss of 5% or more.
Data were derived from Karakus KE, et al. Diabetes Care. 2025;doi:10.2337/dc25-2249.
In new findings from a post hoc analysis, researchers observed that semaglutide can reduce the need for insulin, particularly bolus insulin, among the type 1 diabetes population.
Viral N. Shah
“Semaglutide, even with a low dose of 0.25 mg per week, reduces total insulin dose by almost 20% within the first 4 weeks, and weight loss accounts for only 17% of the reduction in total daily insulin,” Viral N. Shah, MD, professor of medicine in the division of endocrinology and metabolism and director of diabetes clinical research in the Center for Diabetes and Metabolic Diseases at Indiana University School of Medicine, told Healio. “Semaglutide reduces insulin requirements almost independent of weight loss in the early course of the treatment.”
In ADJUST-T1D, participants receiving semaglutide started the drug at a once-weekly 0.25 mg dose for 4 weeks, increasing to 0.5 mg at 4 weeks and 1 mg at 8 weeks for the remainder of the trial. Total daily insulin dose was collected from automated insulin delivery systems at 4, 8, 20 and 26 weeks.
Insulin dose changes
Compared with baseline, adults receiving semaglutide had a 17.7% reduction in total daily insulin dose at 4 weeks, a 20.9% decrease at 8 weeks, a 19.1% drop at 20 weeks and a 22.6% decrease at 26 weeks (P < .001 for all). Adults receiving placebo had no change in total daily insulin dose at 4, 8 and 20 weeks, followed by a 7.1% increase in total daily dose at 26 weeks compared with baseline.
Shah said the reduction in insulin dose was seen even when adults receiving semaglutide were not yet titrated up to the 1 mg dose.
“If a person with type 1 diabetes would like to use a GLP-1 for glycemic outcomes and to reduce their insulin requirements, a low dose (0.25 mg per week) would be sufficient,” Shah said. “When starting semaglutide in a person with type 1 diabetes, reducing the insulin dose by about 20% is reasonable to reduce hypoglycemia risk. Further [insulin] dose reduction with higher doses of semaglutide would be very small.”Daily basal insulin doses dropped by 11.7% at 4 weeks, 12.4% at 8 weeks, 9.8% at 20 weeks and 15.6% at 26 weeks for the semaglutide group compared with baseline. Adults receiving semaglutide also had a reduction in bolus insulin dose of 22.9% at 4 weeks, 29.1% at 8 weeks, 28.7% at 20 weeks and 30.5% at 26 weeks vs. baseline.
Insulin dosage declined for the semaglutide group from 0.72 U/kg per day at baseline to 0.61 U/kg at 4 weeks, 0.59 U/kg at 8 weeks, 0.62 U/kg at 20 weeks and 0.6 U/kg at 26 weeks (P < .001 for all). Insulin dosage did not change for the placebo group.
In mediation analysis, semaglutide was found to have a direct effect on reducing total daily insulin dose by 8.9 U per day to 11.4 U per day, with the largest effect observed at the start of treatment. Weight loss had an increasingly greater effect on the reduction in total daily insulin dose as the study progressed.
Drop in user-initiated boluses
For the semaglutide group, mean carbohydrate intake declined from 137 g per day at baseline to 116 g per day at 4 weeks (P = .015), 99 g per day at 8 weeks (P < .001), 106 g at 20 weeks (P < .001) and 107 g at 26 weeks (P < .001).
Adults receiving semaglutide lowered their number of user-initiated boluses from 4.6 per day at baseline to 3.9 at 4 weeks, 3.8 at 8 weeks, 3.6 at 20 weeks and 3.4 at 26 weeks (P < .001 for all). The number of daily boluses did not change for the placebo group. Among adults using the Tandem Control-IQ or Medtronic automated insulin delivery systems who received semaglutide, mean number of daily correction boluses declined from 4.3 at baseline to 3.4 at 4 weeks (P = .002) and 3.6 at 8 weeks (P = .016). No difference from baseline was seen at 20 and 26 weeks.
Shah said more research is needed to explore the mechanisms behind the reduction in insulin dose with semaglutide.
“Are there any insulin secretory effects of GLP-1s in people with type 1 diabetes,” Shah said. “Would these glycemia and insulin dose reduction effects be sustained over a long period of more than 1 year? What would happen to glycemia and insulin requirements when people with type 1 diabetes stop taking GLP-1s?”
For more information:
Viral N. Shah, MD, can be reached at shahvi@iu.edu.
Sources/Disclosures
Source:
Karakus KE, et al. Diabetes Care. 2025;doi:10.2337/dc25-2249.
Disclosures:
Shah reports receiving honoraria for advising or consulting from Abbott Diabetes Care, Ascensia Diabetes Care, Biomea Fusion, Dexcom, Eli Lilly, Embecta, Insulet, Medtronic, Novo Nordisk, Roche Sanofi, Sequel Med Tech, Tandem Diabetes Care and T1D Scout. Please see the study for all other authors’ relevant financial disclosures.
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