Purpose in Life and Insulin Resistance in a Large Occupational Cohort: Cross-Sectional Associations Using TyG, SPISE-IR, and METS-IR Indices

Background: Insulin resistance (IR) is a key metabolic abnormality underlying type 2 diabetes and cardiometabolic diseases. Although lifestyle and sociodemographic determinants are well described, the role of psychosocial constructs—such as purpose in life—remains insufficiently characterized. No prior study in large occupational samples has examined the associations between purpose in life and IR when evaluated through three complementary indices: the triglyceride–glucose index (TyG), the Single-Point Insulin Sensitivity Estimator for Insulin Resistance (SPISE-IR), and the metabolic score for insulin resistance (METS-IR). Objectives: To analyze the cross-sectional associations between purpose in life and IR indicators in a large working population and determine whether these associations persist after accounting for sociodemographic and lifestyle factors. Methods: A cross-sectional study was conducted among 93,077 Spanish workers aged 20–69 years undergoing routine occupational health examinations. IR was estimated using TyG, SPISE-IR, and METS-IR indices. Purpose in life was assessed using the 10-item Purpose in Life Test and categorized into three groups based on the empirical distribution of scores. Multinomial logistic regression models adjusted for age, sex, social class, smoking, Mediterranean diet adherence, physical activity, and BMI were used to examine associations. Results: Lower purpose in life was consistently associated with higher IR categories across all indices. Compared with individuals reporting high purpose, those with low purpose had higher odds of belonging to the high IR category (TyG ORa 1.59; 95% CI 1.45–1.74; SPISE-IR ORa 1.94; 95% CI 1.76–2.13; METS-IR ORa 2.21; 95% CI 1.98–2.47). Adding purpose in life to sociodemographic and lifestyle models modestly improved discrimination for identifying high IR categories. Conclusions: In this large occupational cohort, purpose in life was independently associated with insulin resistance as measured by three metabolic indices. These findings highlight the relevance of psychosocial factors in metabolic health. Longitudinal studies are needed to clarify temporal pathways and assess whether purpose-oriented approaches may contribute to improved metabolic profiles.