Diminished skin blood flow in Type I diabetes: evidence for non-endothelium-dependent dysfunction

The purpose of this study was to quantify the extent to which skin blood flow (SBF) responses to application of endothelium-dependent and -independent vasodilating agents differ between Type I diabetic patients and healthy subjects. Patients and matched controls were studied after an overnight fast. SBF was determined with laser Doppler perfusion imaging before and after iontophoresis of acetylcholine (Ach; endothelium-dependent) and sodium nitroprusside (SNP; endothelium-independent). Basal SBF did not differ significantly between groups. Iontophoresis of ACh and SNP increased SBF 20-fold in controls. In the patients, the increases in SBF following iontophoresis of ACh and SNP were reduced by 18% and 19%, respectively, versus controls (P < 0.05 for both). These data demonstrate that Type I diabetic patients have similar diminished SBF responses to iontophoresis of ACh and SNP, which suggests that non-endothelial-dependent factors are primarily responsible for the diminished SBF responses.