LDL FROM PATIENTS WITH WELL-CONTROLLED IDDM IS NOT MORE SUSCEPTIBLE TO IN-VITRO OXIDATION

Increased susceptibility of LDL to oxidation has been shown to be asso ciated with the presence of coronary heart disease and may account for the accelerated vascular disease seen in diabetes, The response of LD L to in vitro oxidative stress has been proposed as a measure of the p redisposition of LDL to the in vivo subendothelial oxidative stress, I ncreased susceptibility to oxidation has been demonstrated recently in diabetic patients with poorly controlled IDDM, Thus, we conducted stu dies to determine whether the increased susceptibility of LDL to oxida tion was secondary to diabetes per se or to the level of glycemic cont rol, Fifteen IDDM patients with good glycemic control and with no evid ence of macrovascular disease or proteinuria were compared with health y age-, sex-, race-, and BMI-matched nondiabetic subjects, Fasting blo od glucose levels averaged 12.1 +/- 1.1 (mean +/- SE) vs, 4.9 +/- 0.1 mmol/l in the diabetic versus the control groups, respectively, HbA(1c ) levels averaged 7.7 +/- 0.5 vs, 4.4 +/- 0.2%, reflecting well-contro lled diabetes (P < 0.0001), Total, LDL, VLDL, and HDL cholesterol, tri glyceride, and lipoprotein(a) levels did not differ between the groups , The particle size, lipid composition, fatty acid content, antioxidan t content, and glycation were similar for LDL isolated from both group s, A rapid LDL preparation technique was used to compare LDL susceptib ility to oxidation under the following conditions: final LDL cholester ol concentration of 100 mu g/ml, 5 mu mol/l of CuCl2 at 25 degrees C, There was no difference in the susceptibility to in vitro oxidation of LDL isolated from IDDM patients compared with control subjects, There was no correlation of glycemic control with any of the parameters of the in vitro oxidation of LDL, LDL from patients with well-controlled IDDM does not differ in composition or in susceptibility to in vitro o xidative stress compared with LDL from nondiabetic subjects.