Sociodemographic, Lifestyle, and Social Isolation Correlates of TyG, METS-IR, and SPISE-IR Scores in a Large Spanish Working Population.

Background: Insulin resistance (IR) is a central feature in the pathophysiology of type 2 diabetes and a major determinant of cardiovascular morbidity. While sociodemographic and lifestyle factors are established contributors, the role of social isolation as a potential determinant of IR remains underexplored in working populations. Objectives: To assess the association between sociodemographic variables, lifestyle habits, and social isolation with three validated insulin resistance indexes-Triglyceride-Glucose (TyG), Metabolic Score for Insulin Resistance (METS-IR), and Single Point Insulin Sensitivity Estimator (SPISE-IR)-in a large cohort of Spanish workers. Methods: A cross-sectional study was conducted involving 117,298 workers from occupational health centers across Spain. Sociodemographic data, lifestyle factors (Mediterranean diet adherence, physical activity, and smoking), and social support levels (ENRICHD Social Support Instrument) were recorded. Biochemical and anthropometric parameters were obtained through standardized protocols. Logistic regression models estimated the odds ratios (ORs) and 95% confidence intervals (CIs) for high IR risk across the three indexes, adjusting for potential confounders. Results: Male sex, older age, lower social class, smoking, low Mediterranean diet adherence, physical inactivity, and low social support were independently associated with higher odds of IR in all three indexes. The strongest associations were observed for physical inactivity (OR range 6.21-9.95) and low social support (OR range 1.98-3.76). Although effect sizes varied by index, patterns of association were consistent. Conclusions: Sociodemographic, lifestyle, and psychosocial factors, including social isolation, are strongly associated with insulin resistance in working populations. Integrating social support assessment into occupational health strategies may enhance early detection and prevention of IR and related cardiometabolic diseases.