PLASMA-LIPID PEROXIDATION AND HYPERGLYCEMIA - A CONNECTION THROUGH HYPERINSULINEMIA

Increased lipid peroxidation has been commonly observed in diabetic pa tients as compared to control subjects. However, studies on the relati onship to metabolic control have yielded conflicting results and no da ta are available on the relationship of hyperinsulinaemia to lipid per oxidation. We investigated, in well-characterized groups of 93 patient s with noninsulin-dependent diabetes mellitus, 22 subjects with impair ed glucose tolerance (IGT) and 96 subjects with normal glucose toleran ce (NGT), the determinants of plasma lipid peroxidation measured by pl asma thiobarbituric acid reactive substances (TEARS). These were signi ficantly higher in subjects with ICT (1.04+/-0.48 mu mol(-1)) and in N IDDM patients (1.00+/-0.48 mu moll(-1)) than in those with NGT (0.75+/ -0.46 mu moll(-1); p < 0.05). The glucose tolerance status was the maj or determinant of increased lipid peroxidation even after controlling for the effects of age, sex, body mass index, physical activity, use o f alcohol, smoking, and the use of diuretics. In regression analyses t he major determinants of plasma TEARS were fasting plasma glucose, ins ulin, and apolipoprotein A(1) (inversely) levels. To conclude, plasma TEARS were increased in impaired glucose tolerance and in diabetes and they were related to prevailing plasma glucose and insulin levels, su ggesting a role for insulin resistance in increased lipid peroxidation process. On the contrary, apolipoprotein A(1) may have protective eff ects in this respect.