Endocrine Abstracts

Introduction: Many complications of T2DM, including retinopathy and renal failure, have been associated with glucose and triglyceride metabolism. Hyperglycemia causes oxidative stress mainly due to the enhanced production of mitochondrial reactive oxygen species ROS, non-enzymatic protein glycosylation and glucose autoxidation. Elevated levels of free fatty acids can contribute to oxidative stress by promoting mitochondrial oxidation. Furthermore, oxidative stress caused by hyperglycemia and free fatty acids leads to the activation of stress-sensitive signaling pathways, which impair both insulin secretion and action and promote the development of T2DM.

Aim: The aim of this study is to determine the possible correlation of glucose Glu, cholesterol Chol, HDL-Chol, LDL-Chol, triglycerides TG, plasma uric acid UA and glycosylated hemoglobin HbA1c with the levels of oxidized lipids in plasma and in red blood cells, diabetics and normal patients.

Materials and Methods: The study included 30 T2DM volunteers with plasma Glu levels > 125mg% and HbA1c > 7.0% and 30 normal volunteers who were the control group. Oxidative damage was determined by the thiobarbituric acid TBA method. The assay photometrically measures the malondialdehyde MDA contained in the sample as well as the MDA generated by lipid hydroperoxidases under the hydrolytic reaction conditions. Glu, HDL-Chol, LDL-Chol, TG, UA and HbA1c determinations were performed on a biochemical analyzer.

Results: In the control group, Glu levels were 84±8 mg%, TG 78±28 mg%, HDL 57±8 mg%, LDL 115±27 mg%, UA 5.6±1.5 mg%, HbA1c 5.4 ±0.2%, plasma TBA 0.023±0.013 µmol/l and hemolysate TBA 0.017±0.005 µmol/l. In the diabetic patient group, Glu levels were 152±25mg%, TG 185±50mg%, HDL 40±10mg%, LDL 100±40mg%, UA 6.1±1.5mg%, HbA1c 7.8±0.2%, plasma TBA 0.112±0.043μmol/l and blood plasma TBA 0.015±0.005μmol/l. TBA levels in the control group were statistically significantly lower than those in the diabetic group. In the group of diabetic patients, a positive correlation was found with Glu -HbA1c (r=0.889, P-value<0.001), LDL–Chol (r=0.686, P-value=0.01), LDL–HDL (r=0.649, P-value=0.016), TG–Glu(r=0.548, P-value=0.042), plasma TBA–HbA1c(r=0.549, P-value=0.023), plasma TBA-Glu (r=0.593, P-value<0.001) and negative correlation HDL-TG (r=-0.684, P-value=0.01), LDL-TG (r=-0.72, P-value=0.006). In the control group, a positive correlation was found between LDL – Chol (r=0.964, P-value<0.001) and plasma TBA-TG (r=0.773, P-value=0.009).

Conclusions: The present study in the Greek population showed increased TBA levels in the T2DM group and a positive correlation with Glu and HbA1c levels. Further correlation with other markers would complete the study.