Comparison effect of hyperglycaemia induced mixed meal tolerance and oral glucose tolerance test on body oxidative stress

Abstract Objectives The mixed meal tolerance test (MMTT) and oral glucose tolerance test (OGTT) are used in the diagnosis of prediabetes and hypoglycaemia. Data suggest that oxidative stress caused by hyperglycaemia during OGTT may have adverse metabolic effects in prediabetic patients. In this study, we aimed to evaluate oxidant and antioxidant levels in OGTT and MMTT. Methods The study included 72 patients who underwent MMTT and OGTT at one-week intervals. Total Oxidant Status (TOS) and total antioxidant status (TAS) levels were analysed in samples taken from patients at zero, first and second hours of MMTT and OGTT and Oxidative Stress Index (OSI) was calculated, and the data were compared. Results OGTT and MMTT results were compared with each other within the patient group. While significant differences were found between first-hour glucose, TOS and OSI values (p<0.01), no significant differences were observed for zero and second-hour values (p>0.05). There was no significant difference in TAS values (p>0.05). When zero, first, and second-hour results were compared for OGTT and MMTT within the same test, no significant differences were found for the other parameters except for glucose (p<0.01 for both tests). The correlation between glucose and TOS, TAS and OSI values in MMTT and OGTT was not found. Conclusions Our study concludes that the body experiences more oxidative stress in the first hour following an OGTT than the oxidative stress induced by hyperglycaemia in a mixed-meal diet. Further research is needed to determine whether oxidative stress in the first hour triggers dysmetabolic events in the body.