Reduced aortic wall stress in diabetes mellitus ‐ a contributor for the low incidence of abdominal aortic aneurysm?

Objective Most risk factors are similar for abdominal aortic aneurysm (AAA) and atherosclerosis. Diabetes mellitus is a risk factor for atherosclerosis, but diabetic patients seldom develop AAA. Increased aortic wall stress seems to be an etiologic factor in the formation of AAA in man. Our hypothesis was that, in diabetic patients, the relation between pressure, diameter and wall thickness in the abdominal aorta changes in a protective manner, thus reducing wall stress and the risk of AAA development. Design and methods 41 diabetics and 47 healthy controls were investigated. The intima‐media thickness (IMT) and lumen diameter (LD) of the infrarenal abdominal aorta (AA) were studied with B‐mode ultrasound. Diastolic blood pressure (DBP) was measured non‐invasivly. The law of LaPlace (DBP*LD/IMT) was used to calculate wall stress. Results Age, DBP, and LD in the AA were not significantly different in the diabetic patients than in healthy controls. IMT in the AA was larger in diabetics than in healthy controls 0.89±0.17 vs 0.73±0.1 mm, p<.001. Aortic wall stress was reduced in the diabetic patients, 7.7±1.6*105 vs 9.7±1.9 *105 dynes/cm2, p<.001 Conclusion Wall stress in the abdominal aorta is reduced in diabetes mellitus, which coincides with the fact that epidemiological studies have shown a decreased risk of aneurysm development. The reduced wall stress may contribute to the low incidence of AAA in diabetic mellitus.