To determine whether changes in hand skin blood flow in diabetic men could be demonstrated with liquid crystal contact thermography and to assess the relative effects of autonomic neuropathy and microangiopathy on these changes.
Thirty-four diabetic and 12 age-matched nondiabetic men comprised the study. The diabetic men were categorized according to standard cardiovascular autonomic function tests and the presence or absence of background or proliferative retinopathy and/or proteinuria. Bilateral hand thermograms were measured at rest and after immersion of the right hand in ice-cold water.
Diabetic men with definite or severe autonomic neuropathy (n = 13) had a high frequency of anisothermal baseline thermograms (77 vs. 25% in nondiabetic subjects, P < 0.05). After ice-cold water immersion, right-hand recovery was abnormally slow (514 ± 157 arbitrary U, area under the curve) compared with nondiabetic men (685 ± 135 arbitrary U, P < 0.01). Diabetic men with proliferative retinopathy (n = 8) all had definite or severe autonomic neuropathy and showed the same abnormalities. Diabetic men with nor or early autonomic changes showed normal thermographic patterns.
These results are consistent with increased palmar arteriovenous shunt blood flow or capillary closure in the hands of diabetic patients with definite or severe autonomic neuropathy. They indicate that thermoregulatory reflex changes in hand skin blood flow are controlled by the autonomic nervous system. It is possible, however, that diabetic microangiopathy, associated with the presence of proliferative retinopathy, also independently affects hand skin blood flow.
