Clinical usefulness of human serum nonmercaptalbumin to mercaptalbumin ratio as a biomarker for diabetic complications and disability in activities of daily living in elderly patients with diabetes.

ABSTRACT

BACKGROUND: Oxidative stress may play an important role in the development of diabetic complications. The ratio of human nonmercaptalbumin (HNA; oxidized form) to human mercaptalbumin (HMA; reduced form) has attracted attention as an indicator for systemic redox states. In this study, we measured the ratio in elderly patients with diabetes and evaluated its association with diabetic complications and disability in activities of daily living (ADL disability). METHODS: One hundred twenty-six elderly patients with diabetes, aged 70 years and older, under medical care at Yukuhashi Central Hospital from April 2018 to June 2018, were continuously recruited. HNA%, defined as HNA / (HNA + HMA) × 100, was measured by a high-performance liquid chromatography method. First, multivariate regression analysis was performed to evaluate which variables were significant determinants for HNA%. Next, to evaluate the association of HNA% with ADL disability, logistic regression analysis in various models was performed. Then we plotted the receiver operating characteristic (ROC) curve and calculated the under area the curve (AUC), sensitivity, and specificity in each model. RESULTS: In elderly patients with diabetes, multiple regression analysis showed that serum bilirubin levels and albumin levels, both of which are major endogenous anti-oxidants, and chronic renal failure (or proliferative nephropathy) were significantly associated with HNA%, suggesting that HNA% may be a good biomarker for oxidative stress in those patients. We then evaluated the association of HNA% with ADL disability in various logistic regression models. Model using only HNA% showed that it was a significant determinant for ADL disability (OR 1.158, 95% CI 1.077-1.244, P < 0.001). Model using HNA% and age showed that both variables were significant determinants for ADL disability (OR 1.160, 95% CI 1.069-1.258, P < 0.001; OR 1.258, 95% CI 1.110-1.427, P < 0.001, respectively). ROC analysis showed that the AUC of HNA% alone was 0.765. The AUC of model using HNA% and age was further increased to 0.866. CONCLUSIONS: HNA% was significantly associated with diabetic complications and ADL disability, thereby may be clinically useful as an oxidative stress marker in elderly patients with diabetes.