Research Summary

Once-Weekly Semaglutide Improves Glycemic Control and Weight in Adults With Type 1 Diabetes

Kate Young

Key Highlights

  • In a 26-week double-blind trial, semaglutide plus automated insulin delivery improved time in range and reduced weight in adults with type 1 diabetes.
  • 36% of participants on semaglutide achieved the primary composite endpoint versus 0% on placebo (P < .001).
  • No diabetic ketoacidosis was reported; rates of severe hypoglycemia were similar between groups.

Introduction

A 26-week, double-blind, randomized trial published in NEJM Evidence evaluated the efficacy and safety of once-weekly semaglutide in adults with type 1 diabetes (T1D) and obesity using automated insulin delivery (AID) systems. The ADJUST-T1D trial, funded by Breakthrough T1D, assessed whether semaglutide could improve glycemic control and weight outcomes in this population—a setting in which its use remains unapproved.

Study Findings

The ADJUST-T1D trial enrolled 72 adults with type 1 diabetes and a body mass index (BMI) ≥ 30 kg/m². Participants were randomized 1:1 to receive semaglutide up to 1 mg weekly or placebo, in combination with AID.

The primary composite endpoint—time in range (70–180 mg/dL) > 70%, time below 70 mg/dL < 4%, and ≥ 5% weight reduction—was achieved by 36% of participants on semaglutide versus none on placebo (difference, 36 percentage points; 95% CI, 20.6–52.2; P < .001).

Additional analyses demonstrated:

  • HbA1c reduction: −0.3 percentage points (95% CI, −0.6 to −0.05).
  • Time in range improvement: +8.8 percentage points (95% CI, 3.9–13.7).
  • Weight loss: −8.8 kg (95% CI, −10.6 to −7.0).

Safety outcomes were favorable. Two severe hypoglycemia events occurred in each group, and no cases of diabetic ketoacidosis were reported.

Clinical Implications

These findings suggest that adjunctive semaglutide therapy may enhance glycemic control and facilitate weight reduction in adults with T1D using modern insulin delivery technology. Improvements in continuous glucose monitoring metrics—specifically increased time in range and reduced hypoglycemia—may translate to better long-term metabolic stability and reduced complication risk.

Given the high prevalence of overweight and obesity in adults with T1D, semaglutide’s effects on both glucose and weight outcomes could represent a meaningful clinical advance. However, further research in larger populations and across varying BMI ranges is necessary before considering semaglutide as an adjunctive therapy in T1D management.

Expert Commentary

According to the study investigators, “In adults with type 1 diabetes and obesity, semaglutide treatment, compared with AID use alone, significantly improved achievement of a composite of time in range of greater than 70%, with time below range of less than 4%, and a 5% body weight reduction.”

Conclusion

In the ADJUST-T1D trial, once-weekly semaglutide improved key glycemic and weight outcomes in adults with type 1 diabetes using automated insulin delivery.

Reference:
Shah VN, Akturk HK, Kruger D, et al. Semaglutide in adults with type 1 diabetes and obesity. NEJM Evid. 2025;4(8):EVIDoa2500173. doi:10.1056/EVIDoa2500173