Research report: Shift work and TyG-metabolic obesity indices on hypertension incidence among male steelworkers: a prospective cohort study

Male steelworkers who work rotating shifts face a sharply elevated risk of developing hypertension, and a new prospective cohort study from Tangshan, China, suggests that a cluster of metabolic markers may explain part of that danger. The research, published in BMC Public Health, followed 4,345 male steelworkers for roughly seven years and found that both shift work exposure and triglyceride-glucose-based metabolic obesity indices were independently and jointly linked to new cases of high blood pressure. During that period, 1,685 men developed hypertension, a cumulative incidence of 38.78 percent.

The study focused on five indices derived from the triglyceride-glucose (TyG) index, each combining blood lipid and glucose measures with an anthropometric marker of body fat: TyG-WWI (weight-adjusted-waist index), TyG-WHtR (waist-to-height ratio), TyG-BMI, TyG-WC (waist circumference) and TyG-CVAI (Chinese visceral adiposity index). Using multivariate Cox regression, the researchers found that current shift work, three-shift rotation, and a high weighted shift index (WSI) — a quantitative measure of cumulative shift exposure — were all significantly associated with increased hypertension risk, with hazard ratios ranging from 1.304 to 2.609 across exposures, all statistically significant at P < 0.001. High scores on each of the five TyG-metabolic obesity indices likewise predicted hypertension, indicating that the metabolic fingerprint of shift workers carries independent prognostic weight.

Restricted cubic spline analyses revealed that both the weighted shift index and the TyG indices showed nonlinear, positive dose-response relationships with hypertension incidence. In practical terms, risk did not climb smoothly and indefinitely; instead, the curves suggest threshold effects, points beyond which additional shift exposure or metabolic deterioration translates into a steeper rise in blood pressure risk. Identifying such thresholds could help occupational health programs set monitoring priorities before workers cross into high-risk territory.

The interaction analyses added a further layer of concern. The weighted shift index showed significant multiplicative interactions with most of the TyG indices, meaning the combined effect of shift work and metabolic obesity exceeded what either factor alone would predict. Mediation analysis then tested whether the TyG indices lie on the causal pathway between shift work and hypertension.

TyG-WWI and TyG-CVAI each partially mediated the relationship, accounting for mediation proportions of 27.352 percent and 27.497 percent respectively. To quantify which components mattered most, the team applied weighted quantile sum (WQS) regression, which assigns risk weights to correlated exposures. TyG-CVAI carried the highest weight at 32.85 percent, marking visceral adiposity — fat wrapped around internal organs — as the dominant metabolic signal in this cohort.

The authors conclude that hypertension risk among male steelworkers is closely tied to both the weighted shift index and TyG-metabolic obesity indices, with threshold effects and synergistic interactions shaping the risk landscape. They recommend incorporating WSI and TyG-CVAI into occupational risk assessment frameworks and prioritizing routine monitoring of triglycerides, fasting blood glucose and HDL cholesterol among shift-working steelworkers. As an observational cohort study in a single industrial population of men, the findings cannot prove causation or generalize directly to women or other industries, but they offer a concrete, measurable set of biomarkers that factories and clinics could begin tracking now to catch hypertension before it takes hold.

Subject of Research: Prospective cohort study of shift work and TyG-metabolic obesity indices as predictors of hypertension incidence in male steelworkers

Article Title: Shift work and TyG-metabolic obesity indices on hypertension incidence among male steelworkers: a prospective cohort study

Article References: Zhang, H., Liu, L., Zhang, K., Zhang, M., Wang, D., Ma, X., Yu, M., & Wu, J. (2026). Shift work and TyG-metabolic obesity indices on hypertension incidence among male steelworkers: a prospective cohort study. BMC Public Health. https://doi.org/10.1186/s12889-026-29668-0

Image Credits: AI Generated

DOI: 10.1186/s12889-026-29668-0

Keywords: shift work, hypertension, TyG index, metabolic obesity, steelworkers, occupational health, visceral adiposity, cohort study, cardiovascular risk, insulin resistance, weighted shift index, China