Introduction Workplace social capital (WSC) is hypothesised to be beneficial for employee health. We sought to examine the association between changes in WSC in relation to changes in HbA1c levels.

Methods Analyses included 2778 men and 684 women aged 65 and under working at six companies in Japan from the J-HOPE Study. The first survey was conducted between October 2010 and December 2011, and two follow-up surveys were conducted at approximately annual intervals. Questionnaires inquiring about workplace social capital and other characteristics were administered at each survey. Blood samples were obtained from participants at baseline and at the following two surveys. Linear regression analysis was performed to assess the cross-sectional and longitudinal association between WSC and HbA1c levels using Generalised Estimating Equations.

Result For women, higher level of WSC was cross-sectionally associated with lower HbA1c (standardised regression coefficient (β) −0.020, 95% CI: −0.033 to −0.007). Longitudinally, similar associations were observed (β −0.016, 95% CI: −0.030 to −0.003). No association was found among men. All explanatory variables were standardised before inclusion in each analysis.

Discussion WSC may have beneficial effects on glycometabolism in working women. The gender difference in associations may be partially explained by the socio-cultural context. Our findings lend weight to the notion that the pattern of association between WSC and HbA1c is both culturally contingent and gender-specifi.