Modification of the effect of glycemic status on aortic distensibility by age in the multi-ethnic study of atherosclerosis.

Elevated serum glucose from diabetes mellitus (DM) or impaired fasting glucose shares many mechanisms with aging that decrease aortic distensibility (AD), such as glycation of the extracellular matrix. However, few data compare the simultaneous effects of elevated serum glucose and aging on AD. To study this, we examined the relationship among fasting glucose status, age, and AD in the Multi-Ethnic Study of Atherosclerosis: a multiethnic cohort of individuals aged 45 to 84 years without clinical cardiovascular disease. In the Multi-Ethnic Study of Atherosclerosis, participants with normal fasting glucose (n=2270), impaired fasting glucose (n=870), and DM (n=412) underwent MRI assessment of proximal thoracic aortic distensibility. This sample was 46% male, 42% white, 30% black, 11% Asian, and 17% Hispanic. The relationship among glucose status, age, and AD was analyzed with general linear models by adjusting for factors influential on AD. An interaction term was used to determine whether age modified the effect of glucose status on AD. AD was lowest among those with DM. The interaction term was significant (P=0.024). Comparing participants <65 years of age, AD was different between normal fasting glucose and DM (P<0.01) and between normal fasting glucose and impaired fasting glucose (P=0.02). In those >65 years of age, the fasting glucose group was no longer a significant predictor of AD. Our data indicate that there are overall differences in AD among DM, impaired fasting glucose, and normal fasting glucose. However, age modified the effect of glucose status such that differences between the groups diminished with advancing age.