Regulation of the Cutaneous Circulation
Local temperature has an important role in the control of the skin circulation in humans, and can change skin blood flow from zero to maximal levels. Vasodilation to local warming of the skin includes important roles for sensory nerves and nitric oxide. In individuals with type 2 diabetes mellitus (DM), cutaneous vascular function is impaired, but the mechanisms are not well understood.
To test whether local warming vasodilation is altered in type 2 DM, and to test whether hyperglycemia per se has a role in altered local control of skin blood flow in diabetes.
1. We used nonpainful local warming (42°C) of the skin in combination with laser-Doppler measurement of skin blood flow in individuals with type 2 DM and in age-matched controls. 2. In separate studies, we measured responses to similar local warming in healthy individuals during acute hyperglycemia induced by intravenous infusion of glucose with simultaneous insulin, somatostatin, glucagon and growth hormone infusions to keep all other hormones at baseline physiological levels.
Preliminary results indicate diminished vasodilation to nonpainful local warming in patients with type 2 DM compared to controls, including a decrease of ∼20% in both the initial peak (sensory nerve mediated) and final plateau (NO dependent) phases of the response. Acute hyperglycemia in healthy subjects did not alter cutaneous vasodilation to local warming.
Cutaneous vasodilation to nonpainful local warming is impaired in type 2 DM. Although one episode of acute hyperglycemia did not affect this response in healthy subjects, this impairment in patients may be a result of repeated episodes or higher levels of hyperglycemia in the development of the disease. Supported by NIH DK-29953, HL-63328, AR-08610 and GCRC grant RR-00585 (to the Mayo Clinic).