Correlations between biomarkers of oxidative stress, glycemic control and insulin resistance in women with type 2 diabetes

Abstract

Background. The main characteristic of type 2 diabetes mellitus (T2DM) is hyperglycemia due to insulin resistance. Enhanced oxidative stress owing to increased oxygen free radicals and/or reduced antioxidant defense has very important roles in T2DM development and also most of its complications. The aim of the current study was to evaluate correlations between biomarkers of oxidative stress, glycemic control and insulin resistance in women with T2DM. Materials and methods. Seventy nine women with T2DM were included in the current study and fasting blood samples were collected. Hemoglobin A1c (HbA 1c ); glucose; oxidative stress biomarkers including malodialdehyde, 8-isoprostane, catalase and total antioxidant capacity (TAC) were measured. The adiponectin/leptin (A/L) ratio and the homeostasis model assessment of beta-cell function (HOMA-B) were calculated. The results were considered significant when the p-value was less than 0.05. Results. Serum levels of TAC showed a significant positive correlation with the A/L ratio (r = 0.261, p = 0.02). A significant negative correlation was observed between values of HbA 1c and TAC (r = –0.300, p = 0.007). However, HbA 1c correlated positively with 8-isoprostane (r = 0.236, p = 0.036). Values of HOMA-B correlated negatively with values of HbA 1c (r = –0.327, p = 0.003). Serum levels of 8-isoprostane were significantly higher in obese (BMI > 30 kg/m 2 ) women than in non-obese (BMI < 30 kg/m 2 ) women (p = 0.032). Values of catalase (p = 0.022) and HOMA-B (p = 0.009) were significantly lower in women with HbA 1c ≥ 7.6% compared with women with HbA 1c < 7.6%. Conclusions. In summary, chronic hyperglycemia results in oxidative stress. This situation might lead to less beta cells function. In addition, low levels of the A/L ratio were associated with increased oxidative stress.