Higher oxidative balance score is associated with better glycemic control among Iranian adults with type-2 diabetes

The oxidative balance score (OBS) is a measure of combined pro- and anti-oxidant exposure status, with a higher OBS representing a predominance of anti- over pro-oxidant exposures. We aimed to examine the association of OBS and glycemic control among Iranian adults with type-2 diabetes. This cross-sectional study was conducted among 476 adults with type-2 diabetes (mean age 56.2 y; 66.6% female). Fasting glycosylated hemoglobin (HbA 1c ) and serum glucose (FSG) levels were measured as markers of glycemic control. The OBS was calculated by combining information from a total of 18 a priori selected pro- and anti-oxidant components. These components were comprised of the following four categories: dietary anti-oxidants (i.e., dietary intakes of selenium, fiber, retinol, α-carotene, β-carotene, β-cryptoxanthin, lutein, lycopene, vitamin D, vitamin E, folate, and vitamin C); dietary pro-oxidants (i.e., dietary intakes of iron, saturated fatty acid, and poly-unsaturated fatty acid); non-dietary anti-oxidants (i.e., physical activity); and non-dietary pro-oxidants (i.e., smoking and obesity). After adjusting for several potential confounders in the analysis of covariance models, multivariable adjusted means of HbA 1c and FSG of subjects in the highest tertile of OBS were significantly lower than those in the lowest tertile (for HbA 1c : mean difference –0.73%; and for FSG: mean difference –10.2 mg/dL; both P < 0.050). The findings suggest that a higher OBS, indicating a predominance of anti- over pro-oxidant exposures, is associated with a better glycemic control among Iranian adults with type-2 diabetes. However, future prospective studies of adequate methodological quality are warranted to confirm these findings.