Hemoglobin concentration and incident metabolic syndrome: a population-based large-scale cohort study.

Previous cross-sectional studies revealed an association between hemoglobin concentration and a prevalence of metabolic syndrome (MetS). However, the association between hemoglobin concentration and incident MetS remains to be elucidated. Thus, the aim of this study was to investigate the association between hemoglobin concentration and incident MetS. We enrolled 2695 subjects (1454 men and 1241 women) and performed 8-year follow-up cohort study. MetS was diagnosed, according to the joint interim statement, when a subject had three or more of the following components: hypertension; hyperglycemia; hypertriglyceridemia; low high-density lipoprotein cholesterol; and abdominal obesity. Logistic regression analyses were performed to assess the impact of hemoglobin concentration on incident MetS by adjusting for age, body mass index, lifestyle factors, including smoking status, habit of alcohol and habit of exercise, systolic blood pressure, fasting plasma glucose, triglycerides, high-density lipoprotein cholesterol, creatinine, and uric acid. The highest (≥157 g/L) and third (151-156 g/L) hemoglobin concentration quartiles were associated with the increased risk of incident MetS compared to the lowest (<145 g/L) hemoglobin concentration quartile after adjusting for covariates in men (multivariate odds ratio (OR) 2.24, 95% CI 1.34-3.85, P = 0.0021 and multivariate OR 2.03, 95% CI 1.21-3.45, P = 0.0070). On the other hand, there was no association between hemoglobin concentration and incident MetS in women. Hemoglobin concentration was a novel risk marker for incident MetS in men.