Research Summary

BMI Normalization Associated With Lower Risk of Type 1 Diabetes Among Youth

Edited by:
Ashton L. Stahl

Key Highlights

  • BMI normalized in 26.8% of 833 autoantibody-positive participants with baseline overweight or obesity.
  • BMI normalization was associated with a 48.4% lower adjusted risk of progression to stage 3 type 1 diabetes.
  • The association was primarily observed in youth, particularly boys younger than 12 years and girls aged 12 to younger than 18 years.
  • BMI normalization was associated with reduced progression from stage 1 to stage 2 and stage 2 to stage 3.

BMI normalization was associated with a substantially lower risk of progression to clinical type 1 diabetes among autoantibody-positive individuals with overweight or obesity, primarily in youth, according to a study published in Diabetes Care. The association was not significant among adults.

Researchers analyzed 833 participants in the international TrialNet Pathway to Prevention prospective cohort who had overweight or obesity at baseline, at least 3 BMI measurements, and stage 0, 1, or 2 type 1 diabetes. Participants were followed with autoantibody testing, hemoglobin A1c measurements, and oral glucose tolerance tests at 6- or 12-month intervals. Cox proportional hazards models evaluated progression to stage 3 disease, with reported primary analyses adjusted for baseline age, BMI z-score, and type 1 diabetes stage.

Study Findings

At a median follow-up of 4.1 years, BMI normalized in 223 participants (26.8% of the cohort). BMI normalization was associated with lower risk of stage 3 type 1 diabetes in both unadjusted (hazard ratio [HR], 0.652; P = .022) and adjusted analyses (HR, 0.516; P < .001).

The association was primarily observed among participants younger than 18 years (n = 421; HR, 0.497; P = .001), including boys younger than 12 years (n = 140; HR, 0.272; P < .001) and girls aged 12 to younger than 18 years (n = 73; HR, 0.232; P = .043). No significant association was identified among adults (n = 412; P = .130). BMI normalization was also associated with lower adjusted risks of progression from stage 1 to stage 2 (HR, 0.620; P = .010) and stage 2 to stage 3 (HR, 0.347; P = .003). The association for progression from stage 0 to stage 1 did not reach statistical significance (P = .051).

Clinical Implications

According to the study authors, the findings suggest that BMI normalization may be a modifiable factor influencing progression to stage 3 type 1 diabetes and support consideration of clinical trials evaluating obesity-directed strategies in at-risk individuals. The stage-specific results suggest that BMI normalization may be more relevant once islet autoimmunity is established.

The authors noted that relatively few participants normalized their BMI, limiting statistical power in some subgroup analyses, while assessment intervals prevented determination of the precise timing and duration of BMI changes. The study also lacked systematic information about lifestyle interventions, anti-obesity medications, and bariatric procedures, preventing researchers from determining how BMI normalization occurred.

Expert Commentary

“Among autoantibody-positive individuals with overweight or obesity, BMI normalization was associated with a 48.4% lower risk of clinical T1D, primarily in youth,” the researchers concluded.

Reference

Redondo MJ, Cuthbertson D, Gupta R, et al. BMI normalization is associated with lower risk of progression to type 1 diabetes, primarily in youth. Diabetes Care. 2026;49(9):1-9. doi:10.2337/dc26-0833