ABSENCE OF INCREASED SUSCEPTIBILITY OF LDL TO OXIDATION IN TYPE-1 DIABETICS

Insulin-dependent diabetics have a greatly increased risk of developin g premature coronary artery disease which is not entirely explained by known risk factors. A possible explanation may be enhanced oxidative modification of low density lipoprotein (LDL). The aim of this study w as to determine firstly, whether or not LDL from moderately well contr olled type 1 diabetics is more readily oxidisable than LDL from health y non-diabetics and, secondly, to assess whether potential predictors of LDL oxidisability differ between type 1 diabetics and controls. Twe nty type I diabetic men were carefully matched with healthy non-diabet ic men on the basis of age and body mass index and each pair attended the department on the same morning for blood sampling. LDL oxidisabili ty was assessed using both copper in PBS, 15 and 30 mM glucose, and wi th AAPH. There was no difference between type 1 diabetics and controls in the susceptibility of the LDL to either copper-dependent or non-tr ansition metal-dependent oxidation. Furthermore, there was no differen ce between the groups for LDL vitamin E content, LDL fatty acid compos ition in cholesteryl esters, triglycerides or phospholipids, or LDL co pper reductive capacity, but LDL glycation was elevated in the IDDM su bjects. Given the absence of increased LDL oxidisability in these subj ects, the recommendation of vitamin E supplementation in type 1 diabet ics should be considered a secondary priority to achieving adequate gl ucose control.