RESUMO
Aims: To analyse the causal relationships of nutrition intake and physical activity on haemoglobin A1c (HbA1C) in patients diagnosed with type 2 diabetes mellitus (T2DM) stratified by gender and ethnicity. Materials and Methods: An historical cohort of patients with diagnosed T2DM (n = 2831) was extracted from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 public database, including but not limited to, measurements of physical activity, nutrition, body mass index (BMI) and HbA1c. Multivariate analyses and path analyses were employed to estimate the regression coefficients and path coefficients (ρ) of causal path models of physical activity and nutrition intake on HbA1c stratified by gender and three ethnicity groups (ie non-Hispanic white, non-Hispanic black and Mexican American). Results: A significant causal path from increased physical activity to increased magnesium (Mg) intake to decreased HbA1c was found. In addition, increased physical activity significantly decreased BMI, which further decreased HbA1c. These results varied by gender and ethnicity but were directionally consistent. Physical activity decreased HbA1c through BMI for males and through Mg intake for females. Mexican American decreased HbA1c through Mg intake, while non-Hispanic black had an increased HbA1c due to its ethnicity and through increased BMI. Conclusions: The beneficial effects of physical activity on decreased HbA1c were mediated through the increased Mg intake and decreased BMI. This aligned with recent investigations of the inverse causal association of Mg intake with insulin resistance and with decreased inflammation.