ASSOCIATION BETWEEN IMPAIRED GLUCOSE-TOLERANCE AND CIRCULATING CONCENTRATION OF LP(A) LIPOPROTEIN IN RELATION TO CORONARY HEART-DISEASE

Objective-To examine whether impaired glucose tolerance and raised Lp( a) lipoprotein concentrations are associated in subjects with coronary artery disease.Design-Study of two subject populations, one with and one without symptomatic coronary artery disease. Case-control analysis of patients with impaired glucose tolerance and normal glucose tolera nce performed in each subject population independently. Setting-A gene ral practice and a hospital ward in Newcastle upon Tyne. Subjects-517 apparently healthy subjects, 13 with impaired glucose tolerance, and 2 45 patients who had undergone coronary artery bypass graft surgery 12 months before, 51 with impaired glucose tolerance. Main outcome measur es-Serum Lp(a) lipoprotein concentration, plasma glucose concentration before and after oral challenge with 75 g glucose monohydrate, and Lp (a) lipoprotein isoforms. Results-In both the asymptomatic subjects an d the subjects with coronary artery disease there was no significant d ifference between subjects with impaired glucose tolerance and subject s with normal glucose tolerance who were matched for age, sex, and bod y mass index in serum Lp(a) lipoprotein concentrations (geometric mean 61 (geometric SD 4) mg/l v 83 (5) mg/l for asymptomatic subjects, 175 (3) v 197 (2) for subjects with heart disease), nor was there any dif ference in the proportion of subjects who had Lp(a) lipoprotein concen trations >300 mg/l (31% v 23% for asymptomatic subjects, 37% v 37% for subjects with heart disease). For both subject groups there was no si gnificant correlation between Lp(a) lipoprotein concentration and plas ma glucose concentration after a glucose tolerance test, nor did Lp(a) lipoprotein concentration vary by quintile of glucose concentration a fter the test. Examination of Lp(a) lipoprotein isoforms in the subjec ts with coronary artery disease revealed an inverse relation between i soform size and plasma Lp(a) lipoprotein concentration, but there was no evidence that impaired glucose tolerance was associated with partic ular Lp(a) lipoprotein isoforms. Conclusion-Raised Lp(a) lipoprotein c oncentrations are not responsible for the association between impaired glucose tolerance and coronary artery disease.