Reducing insulin burden remains a key therapeutic goal in adults with type 1 diabetes mellitus (T1DM) and obesity. A post hoc analysis of the Adjunct Semaglutide Treatment in Type 1 Diabetes (ADJUST-T1D) trial published in Diabetes Care found that semaglutide 1 mg once weekly was associated with lower total daily insulin dose over 26 weeks versus placebo.

ADJUST-T1D was a double-blind, multicenter, randomized, placebo-controlled trial in adults with T1DM and obesity. This secondary analysis evaluated changes in total daily insulin dose (TDD), basal and bolus insulin requirements, carbohydrate intake, and user-initiated bolus counts. Linear mixed models were used for between-group comparisons, and mediation analysis quantified the relative contribution of direct treatment effect and weight loss to insulin dose reduction.

From baseline to week 26, TDD declined by 22.6% (95% CI -28.3 to -17.0) with semaglutide versus placebo. Bolus insulin fell by 30.5% (95% CI -39.5 to -21.5), while basal insulin declined by 15.6% (95% CI -21.5 to -9.7). The basal-to-TDD ratio increased from 0.56 to 0.62 (P<0.001), and insulin dose in units/kg/day decreased from 0.72 to 0.60 (P<0.001).

At week 4, 83% of the reduction in TDD (-11.1 units/day) was attributed to direct treatment effect and 17% (-2.3 units/day) to weight loss. By week 26, the reduction was split between direct effect (-11.4 units/day; 52%) and weight loss (-10.5 units/day; 48%). Daily carbohydrate intake decreased from 137 g to 107 g.

The findings indicate semaglutide produced rapid and sustained insulin dose reductions, with early effects largely independent of weight loss in adults with T1DM and obesity.