Are Ethnic Disparities in HbA1c Levels Explained by Mental Wellbeing? Analysis of Population-Based Data from the Health Survey for England

AIMS: It is unclear how ethnic differences in HbA(1c) levels are affected by individual variations in mental wellbeing. Thus, the aim of this study was to assess the extent to which HbA(1c) disparities between Caucasian and South Asian adults are mediated by various aspects of positive psychological functioning. METHODS: Data from the 2014 Health Survey for England was analysed using bootstrapping methods. A total of 3894 UK residents with HbA(1c) data were eligible to participate. Mental wellbeing was assessed using the Warwick-Edinburgh Mental Well-being Scale. To reduce bias BMI, blood pressure, diabetes status, and other factors were treated as covariates. RESULTS: Ethnicity directly predicted blood sugar control (unadjusted coefficient −2.15; 95% CI −3.64, −0.67), with Caucasians generating lower average HbA(1c) levels (37.68 mmol/mol (5.6%)) compared to South Asians (39.87 mmol/mol (5.8%)). This association was mediated by positive mental wellbeing, specifically concerning perceived vigour (unadjusted effect 0.30; 95% CI 0.13, 0.58): South Asians felt more energetic than Caucasians (unadjusted coefficient −0.32; 95% CI −0.49, −0.16), and greater perceived energy predicted lower HbA(1c) levels (unadjusted coefficient −0.92; 95% CI −1.29, −0.55). This mediator effect accounted for just over 14% of the HbA(1c) variance and was negated after adjusting for BMI. CONCLUSIONS: Caucasian experience better HbA(1c) levels compared with their South Asian counterparts. However, this association is partly confounded by individual differences in perceived energy levels, which is implicated in better glycaemic control, and appears to serve a protective function in South Asians.