To test the hypothesis that skin blood flow responses in the fingertip of diabetic patients are impaired and to examine the role of aging in both healthy control subjects and diabetic patients.
We measured cutaneous blood flow using laser Doppler techniques in 40 people with diabetes and in 20 age- and sex-matched healthy control subjects. To induce vasoconstriction, subjects were asked to perform three 1-min stressor tasks: mental arithmetic, contralateral hand grip, and immersion of the contralateral hand in ice water. To induce vasodilatation, a local heat stimulus of 45 degrees C was applied for 5 min.
Basal blood flow did not differ between groups, but vasoconstrictive responses induced by arithmetic or immersion of the contralateral hand in ice-cold water and vasodilatation induced by local heating were severely impaired in diabetic subjects, compared with healthy control subjects (P < 0.01). These responses correlated with autonomic nerve function and deteriorated significantly with advancing age in control subjects, but not in diabetic subjects. Blood flow in younger diabetic subjects resembled that of older control subjects.
These data demonstrate that diabetes has effects on precapillaries that may by direct or mediated via autonomic nerves, which result in a deficit that resembles premature aging.