Association of metabolic syndrome and its components with suicidal ideation and depression in adults: A nationally representative sample of the Korean population

•We investigated the association of metabolic syndrome with suicidality and depression.•Metabolic syndrome was associated with suicidal ideation.•High glucose and triglyceride level might be risk factors for suicidality and depression.•Self-rated health mediate on the associations of suicidal ideation with hypertriglyceridemia. Few studies have evaluated the association of depressive symptoms and suicidal ideation with metabolic syndrome (MetS) and its components. This study examined the associations of MetS and its components with suicidal ideation and depression and determined the mediation effect of self-rated health (SRH) on these associations. This study was conducted using cross-sectional data on 9867 people (aged ≥ 19 years old) collected in 2014 and 2016 from a nationally representative sample of the Korean National Health and Nutrition Examination Survey. The associations of MetS with suicidal ideation and depression were estimated after adjusting for potential confounding factors using logistic regression analyses, and a mediation analysis by Hayes and Preacher was used to estimate the mediation pathway between such associations through SRH. After adjusting for confounding factors, suicidal ideation was associated with MetS. Depressive symptoms and suicidal ideation were associated with two components of MetS: high triglyceride level and high fasting plasma glucose level. In the mediation analysis, we found a significant mediating effect of SRH on the association between high triglyceride level and suicidal ideation. We cannot elucidate causal relationships because of the cross-sectional design. Our study provides the implication that a high triglyceride level and elevated fasting plasma glucose level may contribute suicidal risk and depressive symptoms in adults and that SRH may contribute to the development of suicidal ideation in adults via the apparent interaction with one of the components of MetS—high triglyceride level.