Impaired glucose tolerance, Type II diabetes mellitus and carotid atherosclerosis: prospective results from the Bruneck Study

Aims/hypothesis. Cardiovascular disease is a well-known severe complication of impaired glucose tolerance and Type II (non-insulin-dependent) diabetes mellitus. The independent contribution of glucose intolerance to cardiovas cular disease and the underlying pathogenic mechanisms are still, however, not clear. Methods. In this prospective population-based study, 826 subjects aged 40-7 9 years underwent high resolution duplex ultrasound examinations of carotid arteries and extensive clinical and laboratory screenings for potential va scular risk factors at baseline and 5 years later. The ultrasound protocol involved measurements of maximum axial diameter of atherosclerotic plaques, if any, in common and internal carotid arteries on both sides and enable d ifferentiation of two main stages in carotid artery disease, termed early n on-stenotic and advanced stenotic atherosclerosis. Intima-media thickness w as assessed at the follow-up examination. Results. Type II diabetes and, to a lesser extent, impaired glucose toleran ce were found to be statistically significant risk predictors of 5-year cha nges in carotid atherosclerosis. These associations were in part independen t of other vascular risk factors typically clustering with glucose intolera nce. Both impaired glucose tolerance and Type II diabetes mellitus were not independently related to early non-stenotic atherosclerosis. In contrast, Type II diabetes mellitus was the strongest single risk predictor of advanc ed stenotic atherosclerosis [odds ratio 5.0 (95% confidence intervals 2.3-1 1.1)] and impaired glucose tolerance was of relevance as well [odds ratio 2 .8 (1.2-6.4)] (p < 0.001). Conclusion/interpretation. Impaired glucose tolerance and, to a greater ext ent, Type II diabetes were strong independent predictors of advanced caroti d atherosclerosis in our prospective population-based study.