Reduced antioxidant potential & sensitivity to oxidation in plasma low density lipoprotein fraction in type 2 diabetes mellitus patients.

BACKGROUND & OBJECTIVES The aim of this study was to investigate LDL oxidation in the ethiopathogenesis of diabetes mellitus. Diabetes mellitus a disease caused due to severe insulin dysfunction, is associated with lipid and protein metabolic disorders. METHODS A total of 90 type 2 diabetes patients were grouped according to their glycoted haemoglobin (HbA1c) values as regulated (<5.7%), poorly regulated (5.7 - 7.7%) and unregulated (>7.7%). Further, a healthy control group of 37 individuals was included for comparison in terms of sensitivity of low density lipoprotein (LDL) to oxidation and measurements of antioxidant potential (AOP). A heparin - citrate precipitation method was used to obtain LDL from the serum samples of patients and control groups. The LDL fractions were exposed to oxidation with CuSO4 and sensitivity to oxidation was evaluated. Ten patients each from regulated and unregulated groups, and 10 healthy controls were examined for antioxidant potential. RESULTS The sensitivity of LDL fraction to oxidation was significantly lower in all diabetic groups compared to the control group. AOP was significantly decreased in unregulated diabetic group compared to the control group. INTERPRETATION & CONCLUSION We hypothesize that oxidant stress increases in diabetes mellitus and oxidant defense systems weaken during the chronic course of the illness. Due to decreased antioxidant potential, that probably shortens the LDL oxidation lag phase, the sensitivity to oxidation appears to be lower in diabetes mellitus patients.