Summary: In this 6-month, open-label, two-arm randomized trial of overweight or obese adults with newly diagnosed type 2 diabetes (100 randomized 1:1, 89 analyzed), both acarbose and vildagliptin lowered plasma trimethylamine N-oxide (TMAO) from baseline (adjusted p<0.05 within each arm). At 6 months TMAO was significantly lower in the acarbose arm than the vildagliptin arm (intergroup p<0.05), and the fall in TMAO tracked with improvements in insulin-resistance measures. There was no placebo arm, and exact effect sizes were not reported in the abstract.
PICO Summary
| Element | Detail |
|---|---|
| Population | Overweight or obese adults with newly diagnosed type 2 diabetes; 100 randomized 1:1, 89 included in analysis. Single-centre, open-label randomized controlled trial, Beijing, China (recruited Dec 2016 to Dec 2017; NCT02999841). |
| Intervention | Acarbose for 6 months (n=44 analyzed; 50 randomized). |
| Comparison | Vildagliptin for 6 months (n=45 analyzed; 50 randomized). Both were active arms; no placebo group. |
| Outcome | Within each arm, plasma TMAO fell significantly from baseline to 6 months (adjusted p<0.05). Between arms, TMAO was significantly lower with acarbose at 6 months (p<0.05). L-carnitine and γ-butyrobetaine rose significantly (p<0.05); betaine and choline did not change significantly. In the acarbose arm, change in TMAO correlated positively with changes in BMI, waist circumference, postprandial glucose, fasting insulin, fasting C-peptide and HOMA-IR (p<0.05). Exact effect sizes, 95% CIs and ARR/NNT were not reported in the abstract. |
Expert Commentary
This small randomized trial reports that two common oral agents each lowered a gut-microbiota-derived metabolite, TMAO, that has been associated observationally with cardiovascular risk, with a larger reduction seen for acarbose. The signal is biologically coherent: acarbose shifts carbohydrate delivery to the distal gut and remodels the microbiota, so an effect on a microbiota-dependent metabolite is plausible. The verdict, however, must stay cautious. This is a surrogate endpoint, not a clinical outcome; lowering TMAO has not been shown to lower cardiovascular events, and the reported correlations with insulin-resistance measures are associational, not proof that TMAO is on the causal pathway. The single most important limitation is the open-label design with no placebo arm, which leaves the within-arm reductions vulnerable to regression to the mean, lifestyle change after a new diabetes diagnosis, and assessment bias. Sample size is modest and roughly a tenth of those randomized were not analyzed. Reassuringly, the work appears investigator-led rather than manufacturer-sponsored, and the effect sizes are not implausibly large. Can I use this with my patients? Not yet to choose a drug for TMAO lowering; it is hypothesis-generating only. A placebo-controlled or hard-outcome trial is needed before TMAO becomes a treatment target.
References
Yang X, Zhang X, Sun C, Zhao C, Kong X, Zhao M, Ji L, Li Y. Effect of acarbose and vildagliptin on plasma trimethylamine N-oxide levels in patients with type 2 diabetes mellitus: a 6-month, two-arm randomized controlled trial. Front Endocrinol (Lausanne). 2025;16:1575087. doi:10.3389/fendo.2025.1575087