Longitudinal associations of serum Irisin and adiponectin with incident metabolic syndrome in middle-aged and older adults over three years.

Irisin and adiponectin have been proposed as potential therapeutic targets due to their roles in enhancing energy expenditure and improving insulin sensitivity. However, their predictive value for metabolic syndrome (MetS) in middle-aged and older adults remains unclear. This prospective cohort study investigated cross-sectional and 3-year longitudinal associations between serum irisin and adiponectin levels and MetS in an aging population. A total of 348 participants from the Hallym Aging Study were analyzed cross-sectionally, and 188 individuals without MetS at baseline were followed longitudinally. Cross-sectionally, each 1-standard deviation (SD) increase in log-transformed irisin was associated with higher odds of MetS (OR 1.35, 95% CI 1.02-1.80), while adiponectin showed an inverse association (OR 0.71, 95% CI 0.54-0.94). Longitudinally, participants in the highest irisin tertile had increased risk of incident MetS (OR 3.85, 95% CI 1.20-13.64), and each 1-SD increase in irisin was associated with higher MetS incidence (OR 2.10, 95% CI 1.17-4.03). However, each 1-SD increase in adiponectin was not significantly associated with MetS after adjusting for confounders. While further studies should confirm our findings, the results presented here suggest that irisin may be a useful predictor of MetS in older adults, while adiponectin's protective role is less clear.