FOREARM ARTERIAL VASCULAR RESPONSIVENESS IN INSULIN-DEPENDENT DIABETIC SUBJECTS

The vascular reactivity of forearm arterioles was measured in 16 contr ol subjects (C) and 30 insulin-dependent diabetic (IDDM) subjects, 16 of whom were shown to have microvascular and/or neuropathic complicati ons (DC) including 8 with autonomic neuropathy (DCa) and 14 were shown to be free of complications (DNC). Forearm blood flow was measured by strain gauge plethysmography basally, following a cold pressor stress and following a period of arterial occlusion (reactive hyperaemia). T he tests were repeated 24 h later following aspirin treatment. Both C and DNC showed a significant reduction in blood flow in the cold press or test (C 0.64 +/- 0.12, DNC 0.89 +/- 0.22 ml/100 ml forearm tissue/m in reduction in flow P < 0.005), while DC showed no significant respon se. Reactive hyperaemia was significantly greater in C than in DNC or DC (8.37 +/- 1.14, 5.51 +/- 1.27 and 4.95 +/- 0.75 ml/100 ml tissue/mi n, respectively, P < 0.02). In the DC group, DCa had significantly les s response than those without autonomic neuropathy. Aspirin treatment restored the response of DNC but not DC to normal, suggesting that the abnormality in the former group may have been due to overproduction o f a vasoconstrictive cyclooxygenase product (such as thromboxane A(2)) . It is concluded that the abnormalities of vasomotor responses in dia betic subjects are complex and are apparently dependent on autonomic n europathy, humoral and perhaps structural changes.