Summary: In this post hoc analysis of the double-blind SUSTAIN China trial (total n=868; Chinese-only n=605), once-weekly subcutaneous semaglutide 0.5 and 1.0 mg was compared with sitagliptin 100 mg once daily as add-on to metformin. Across baseline age, sex, body mass index, HbA1c, diabetes duration and HOMA-beta tertile, the relative efficacy of semaglutide was not significantly modified by most of these characteristics, supporting a consistent treatment effect rather than demonstrating a new efficacy benefit.
PICO Summary
| Element | Detail |
|---|---|
| Population | Adults with type 2 diabetes from the SUSTAIN China randomised trial; post hoc analysis of total population (n=868) and Chinese-only subset (n=605). China. |
| Intervention | Once-weekly subcutaneous semaglutide 0.5 mg and 1.0 mg, added to metformin, over 30 weeks. |
| Comparison | Sitagliptin 100 mg once daily, added to metformin (active comparator; double-blind, double-dummy design). |
| Outcome | Effect modification of HbA1c and body-weight change by baseline subgroup was the primary question. The relative efficacy of semaglutide versus sitagliptin was not significantly affected by most baseline characteristics; attainment of HbA1c below 7.0% (53 mmol/mol) was not affected by baseline HbA1c (p>0.05). Glucose variability (seven-point SMPG standard deviation and derived time-in-range) and HOMA-beta ratio to baseline favoured semaglutide 0.5 and 1.0 mg over sitagliptin (p<0.05). No 95% CI, absolute risk reduction or NNT for a single confirmatory endpoint is reported, as this is a subgroup-consistency analysis. |
Expert Commentary
This post hoc analysis is best read as a consistency check, not a new efficacy trial. The headline message is reassuring but modest: in SUSTAIN China, the advantage of once-weekly semaglutide over sitagliptin on HbA1c and weight was broadly maintained across baseline age, sex, body mass index, glycaemia, diabetes duration and beta-cell function, and target attainment did not depend on starting HbA1c. Secondary signals on glucose variability, derived time-in-range and HOMA-beta favoured semaglutide and are biologically coherent with its mechanism. The central limitation is the design itself. Subgroup analyses from a single randomised trial are exploratory and underpowered to detect true effect modification, so absence of a significant interaction should be interpreted as no strong evidence of heterogeneity rather than proof of uniform benefit; the analysis is associational for the modifier question, and the trial was funded by the manufacturer, with several authors employed by Novo Nordisk. Can I use this with my patients? Yes, cautiously: it supports offering once-weekly semaglutide to a wide range of metformin-treated adults with type 2 diabetes without expecting baseline traits to blunt the response, while recognising the data are Chinese-population specific and confirm rather than extend the primary SUSTAIN China result. Clinicians should anticipate the usual mild-to-moderate gastrointestinal effects and individualise dose titration. Prospective, prespecified subgroup work would strengthen confidence further.
References
Ji L, Lu Y, Shen Z, Hu P, Liu W, Zhang Q, Shi B. Impact of baseline characteristics on the efficacy of once-weekly subcutaneous semaglutide among participants with type 2 diabetes: A post hoc analysis of SUSTAIN China. Diabetes Obes Metab. 2024;26(11):5312-5324. doi:10.1111/dom.15888
