Cutaneous reactive hyperemia in short-term and long-term type I diabetes--continuous monitoring by a combined laser Doppler and transcutaneous oxygen probe.

Using a recently designed combined laser Doppler/transcutaneous oxygen probe postocclusive reactive hyperemia response was investigated in 10 healthy subjects and 33 patients with type I diabetes mellitus. From the foot dorsum sensing site simultaneous recordings of the red cell flux of the superficial skin microvasculature and cutaneous PO2 were obtained at identical measuring position and conditions. Whereas cutaneous PO2 response exhibited an uniform monophasic curve with a significantly reduced percentage increase of PO2 in short-term (p less than 0.05) and in long-term type I diabetic patients (p less than 0.001), four different laser Doppler hyperemic flux patterns were observed. Hyperemia types A and B were biphasic, type C had only a monophasic course. Apparently in type C the initial fast component of the myogenic response is missing; in type D no increase in flux or PO2 could be measured. Comparison of prevalence of these hyperemia types showed a significantly (p less than 0.05) higher prevalence of the monophasic or even absent hyperemic response in type I diabetes. The reduction in viscoelastic properties of the small arteries and arterioles in patients with type I diabetes may account for these changes which is most likely cofactor in the pathogenesis of diabetic microangiopathy.