The mediating effect role of methylmalonic acid on the association between oxidative balance score and diabetic kidney disease: a cross-sectional study from NHANES 2011–2014

Diabetic kidney disease (DKD) is a prevalent complication of diabetes. Methylmalonic acid (MMA) reflects mitochondrial dysfunction. Oxidative balance score (OBS) assesses the pro-oxidant/anti-oxidant propensity of lifestyle. This study explored the associations of OBS and MMA with the risk of DKD. In this cross-sectional study, diabetes patients aged ≥ 20 years were identified from National Health and Nutrition Examination Survey (NHANES) 2011-2014. Dialysis patients, those without serum and urine creatinine/albumin/education/serum vitamin B12/MMA/OBS data were excluded. The weighted logistic analysis evaluated the associations of OBS and MMA with the risk of DKD. Odds ratio (OR) and confidence interval were estimated. In total, 1618 patients were included. The percentage of participants with OBS <20 in the DKD group was higher than the non-DKD group (53.35% vs 44.98%). The percentage of patients with MMA ≥ 151 in the DKD group was higher than the non-DKD group (67.88% vs 42.36%). The risk of DKD was elevated in those with OBS <20 (OR = 1.42, 95% CI: 1.06-1.91). Elevated risk of DKD was observed in patients with MMA ≥ 151 (OR = 2.13, 95% CI: 1.45-3.14). The total effect of OBS on DKD was 1.42 (95% CI: 1.06-1.91). The direct effect of OBS on DKD was 1.38 (95% CI: 1.03-1.85). The percentage of excess risk mediated of MMA on the association between OBS and DKD was 9.52%. In conclusion, MMA potentially played a mediating role in the association between OBS and DKD. The findings may offer an insight for future screening and prevention of DKD.