Background: Both hypertension and diabetes mellitus (DM) increase risk for subclinical and clinical cardiovascular disease (CVD). The relative extents to which hypertension and DM induce subclinical CVD have not been examined, but recent Framingham data suggest that clinical CVD risk in DM is largely attributable to coexistent hypertension.

Methods: We examined subclinical arterial disease (carotid artery hypertrophy, atherosclerosis, stiffness) and incident CVD in a population-based cohort with high rates of DM and CVD.

Results: 2887 participants were divided into 4 groups: normal (n=799), hypertension alone (n=647), DM alone (n=494), and both hypertension and DM (n=947). In multivariable models adjusting for other CVD risk factors and creatinine, arterial hypertrophy and atherosclerosis were significantly greater in the two DM groups and not increased by coexistent hypertension. Although hypertension significantly altered arterial structure and function compared to normal, differences were eliminated by consideration of systolic pressure. Among 2441 participants without CVD at baseline, events occurred in 10.1% of normals, 17.8% with hypertension alone, 25.5% with DM alone, and 29.3% with both. Rates were significantly higher in the 2 DM groups and not increased by coexistent hypertension. Adjusted hazards ratios were 1.69 (p=0.001) for hypertension alone, 3.16 (p<0.001) for DM alone, and 3.85 (p<0.001) for both (p<0.001 for trend).

Conclusions: Both hypertension and DM cause increased subclinical and clinical CVD. The impact of hypertension on CVD is largely attributable to increased distending pressure. Higher rates of vascular hypertrophy, subclinical atherosclerosis and incident CVD in DM are not attributable to coexistent hypertension in this population.