BackgroundBiomarker of insulin resistance, namely triglyceride-glucose index, is potentially useful in identifying critically ill patients at high risk of hospital death. However, the TyG index might have variations over time during ICU stay. Hence, the purpose of the current research was to verify the associations between the dynamic change of the TyG index during the hospital stay and all-cause mortality.MethodsThe present retrospective cohort study was conducted using the Medical Information Mart for Intensive Care IV 2.0 (MIMIC-IV) critical care dataset, which included data from 8835 patients with 13,674 TyG measurements. The primary endpoint was 1-year all-cause mortality. Secondary outcomes included in-hospital all-cause mortality, the need for mechanical ventilation during hospitalization, length of stay in the hospital. Cumulative curves were calculated using the Kaplan–Meier method. Propensity score matching was performed to reduce any potential baseline bias. Restricted cubic spline analysis was also employed to assess any potential non-linear associations. Cox proportional hazards analyses were performed to examine the association between the dynamic change of TyG index and mortality.ResultsThe follow-up period identified a total of 3010 all-cause deaths (35.87%), of which 2477 (29.52%) occurred within the first year. The cumulative incidence of all-cause death increased with a higher quartile of the TyGVR, while there were no differences in the TyG index. Restricted cubic spline analysis revealed a nearly linear association between TyGVR and the risk of in-hospital all-cause mortality (P for non-linear = 0.449, P for overall = 0.004) as well as 1-year all-cause mortality (P for non-linear = 0.909, P for overall = 0.019). The area under the curve of all-cause mortality by various conventional severity of illness scores significantly improved with the addition of the TyG index and TyGVR. The results were basically consistent in subgroup analysis.ConclusionsDynamic change of TyG during hospital stay is associated with in-hospital and 1-year all-cause mortality, and may be superior to the effect of baseline TyG index.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12933-023-01874-9.