Association of short-term glycemic variability with subclinical myocardial injury in hospitalized patients with type 2 diabetes: a retrospective cross-sectional study

Background Subclinical myocardial injury (SMI) represents an early, asymptomatic stage of cardiac damage characterized by elevated high-sensitivity cardiac troponin T (hs-cTnT) levels in the absence of overt ischemia. Glycemic variability has been increasingly recognized as a cardiovascular risk factor beyond chronic hyperglycemia, but its relationship with SMI in type 2 diabetes mellitus (T2DM) remains unclear. Methods This retrospective cross-sectional analysis included 324 hospitalized patients with T2DM consecutively admitted between January 2021 and December 2023 at a tertiary hospital in Southwest China. SMI was defined as hs-cTnT > 14 ng/L without ischemic symptoms or electrocardiographic abnormalities. Clinical, metabolic, and laboratory data were extracted from electronic medical records. Short-term (in-hospital) glycemic variability was quantified using the standard deviation (SD) and coefficient of variation (CV) of all capillary glucose measurements obtained during hospitalization. Univariate and multivariate logistic regression analyses identified independent predictors of SMI. Model discrimination, calibration, and nomogram-based prediction were evaluated. Results Among 324 patients, 128 (39.5%) exhibited SMI. In multivariate analysis, eight variables were independently associated with SMI: age (OR = 1.05, P = 0.001), BMI (OR = 1.10, P = 0.006), diabetes duration (OR = 1.06, P = 0.004), insulin use (OR = 1.72, P = 0.015), SD of glucose (OR = 3.11, P < 0.001), systolic blood pressure (OR = 1.02, P = 0.038), hs-CRP (OR = 1.08, P = 0.009), and eGFR (OR = 0.97, P = 0.003). The predictive model showed good discrimination (AUC = 0.832, 95% CI 0.787–0.877) and good calibration (Hosmer–Lemeshow P = 0.47). A nomogram based on these predictors provided individualized risk estimation with high clinical interpretability. Conclusion Short-term (in-hospital) glycemic variability, as reflected by the standard deviation of inpatient glucose readings, was independently associated with subclinical myocardial injury in hospitalized patients with type 2 diabetes. These findings suggest that glycemic variability may serve as a risk marker for subclinical myocardial injury in hospitalized patients with T2DM; however, causal relationships and temporal ordering cannot be inferred from this cross-sectional analysis.