Cardiorespiratory fitness and visceral fat impact the relationship between psychological fitness and metabolic syndrome in Japanese males with type 2 diabetes mellitus

Background: It has been unclear whether psychological distress and prevalence of metabolic syndrome (MS) is associated independent of cardiorespiratory fitness and/or visceral fat area in patients with type 2 diabetes mellitus (type 2 DM). Methods: Ninety-seven newly diagnosed Japanese men with type 2 DM (aged 26-81) who did not receive any intervention or pharmacological therapy were divided into two groups of highly distressed (HD) and less distressed (LD) by the cutoff point of the General Health Questionnaire (GHQ). In addition, cardiorespiratory fitness (estimated oxygen uptake: V̇O₂ max), visceral fat area (VFA), glucose and lipid metabolism, and resting blood pressure were assessed. MS was defined based on the criteria proposed by the World Health Organization (WHO). The odds-ratios (OR) for the frequency of a low level of fitness, extremely accumulated VFA, metabolic abnormalities, and MS in both groups were calculated using a logistic regression model. Results: The OR for the frequency of a low level of fitness, the top quartile of VFA, hyperinsulinemia, and MS were significantly higher in the HD than in the LD. The significantly high OR of hyperinsulinemia and MS in the HD disappeared after adjusting for VO₂ max and/or VFA. Conclusions: Our study suggests that the association of psychological distress with hyperinsulinemia and MS might depend on cardiorespiratory fitness and/or VFA in Japanese men with type 2 DM.