Purpose: Insulin resistance (IR) and increased oxidative stress (OS) are the characteristics of polycystic ovary syndrome (PCOS). In this study, we aimed to evaluate the effects of oral glucose tolerance (OGTT) and mixed meal tests (MMT) on plasma total oxidant (TOS) and total antioxidant status (TAS) in patients with PCOS and the relationship between these parameters and IR, calculated via homeostasis of model assessment-IR (HOMA-IR) and Matsuda's insulin sensitivity index (ISI) derived from OGTT and MMT.
Methods: Twenty-two patients with PCOS, and age- and body mass index (BMI)-matched 20 women as controls were enrolled into the study. Five-hour OGTT and MMT were performed on different days, and before and after these tests, plasma TOS and TAS levels were investigated. IR was calculated with HOMA-IR and Matsuda's ISI.
Results: HOMA-IR levels were higher in patients with PCOS, compared to controls, while Matsuda's ISI derived from OGTT and MMT was higher in controls. Plasma TOS levels before OGTT and MMT were higher in patients with PCOS than controls, while TAS levels were similar. After OGTT, plasma TOS levels became decreased at 5th hour, when compared to baseline values in PCOS group. Likewise, the same decrement was found in controls, but the decrement was not significant. After OGTT and MMT at 5th hour, no changes were observed in TAS levels, compared to baseline.
Conclusion: Matsuda's ISIs derived from OGTT and MMT can be used instead of each other, and interestingly, we found a decrease in TOS levels after OGTT in patients with PCOS.
Keywords: Insulin resistance; Mixed meal test; Oral glucose tolerance test; Polycystic ovary syndrome; Total antioxidant status; Total oxidant status.