Ethnic/racial determinants of glycemic markers in a UK sample

To investigate possible causes for previously reported glycemia-independent South Asian-white differences in HbA1c. Demographic and laboratory data on non-diabetic patients from primary care were analyzed. Linear regression models measured the association between race/ethnicity and three glycemic measures (HbA1c, fructosamine and fasting plasma glucose), adjusted for a range of hematological, biochemical and demographic factors. Nine hundred and forty-eight patients consisting of 711 white subjects (407 women) and 237 South Asian subjects (138 women) were studied. Unadjusted bivariate analysis showed that South Asians had higher HbA1c concentrations [41 (5.9 %) vs. 40 (5.8 %) mmol/mol (p = 0.011), coefficient 1.21, 95 % CI 0.27, 2.17 (p = 0.011)] similar fructosamine [228.4 vs. 226.7 mmol/L (p = 0.352), coefficient 3.93, 95 % CI 0.79, 7.08 (p = 0.014)] and fasting plasma glucose [5.1 vs. 5.2 mmol/L (p = 0.154), coefficient -0.09, 95 % CI -0.22, -0.04 (p = 0.156)] concentrations than whites. South Asians also had lower hemoglobin, ferritin and vitamin B12 concentrations than whites. After adjustment for independent variables, South Asian ethnicity was associated with higher HbA1c concentrations [0.89, 95 % CI 0.06-1.72 (p = 0.035)], higher fructosamine levels [3.93, 95 % CI 0.79, 7.08 (p = 0.014)] and lower fasting plasma glucose concentrations [-0.12, 95 % CI -0.26, -0.02 (p = 0.026)] compared to white race. The increased prevalence of hematological abnormalities in South Asians and their higher adjusted HbA1c and fructosamine but lower fasting glucose levels compared to white subjects suggest that ethnic differences in glycation markers may, in part, be due to a combination of erythrocyte factors and glycemia-independent glycation.