Diabetes–TyG interaction and mortality in critical cerebrovascular disease: a retrospective cohort study

Critically ill cerebrovascular disease (CVD) patients face high mortality, yet modifiable prognostic factors remain underexplored. The triglyceride-glucose (TyG) index has emerged as a surrogate marker of insulin resistance, but its association with mortality in neurocritical care and its interaction with diabetes status remain unclear. This retrospective cohort study analyzed 2,584 CVD adults from the MIMIC-IV database (2008–2019). The TyG index was calculated from admission glucose and triglyceride values. Multivariable Cox models assessed TyG-mortality associations, with interaction and stratified analyses by diabetes status. Outcomes included 30-, 90-, and 365-day all-cause mortality. In the overall cohort, TyG showed no significant association with 30-day (HR 1.15, 95%CI 1.00–1.32) or 365-day mortality (HR 1.11, 95%CI 0.98–1.24), with a borderline association at 90 days (HR 1.14, 95%CI 1.00–1.30). However, diabetes significantly modified this effect ( P for interaction = 0.033, 0.004, and 0.005 at 30, 90, and 365 days, respectively). In non-diabetic patients, each TyG unit increment was associated with significantly higher mortality at all time points (30-day: HR 1.25, 95%CI 1.04–1.50; 90-day: HR 1.26, 95%CI 1.07–1.49; 365-day: HR 1.21, 95%CI 1.03–1.40), whereas no association was observed in diabetic patients. Diabetes critically modifies the TyG-mortality relationship in CVD. The TyG index may serve as a prognostic biomarker primarily in non-diabetic patients, suggesting that diabetes-stratified approaches warrant further investigation in neurocritical care.