POSTURALLY INDUCED VASOCONSTRICTION IN DIABETES-MELLITUS

In healthy subjects, standing elicits a reduction in blood flow to the skin of the foot. In adults with insulin dependent diabetes this post urally induced response is deficient, resulting in capillary hypertens ion when the foot is in the dependent position (that is, below heart l evel). Such functional abnormalities of the microcirculation in diabet es may precede any evidence of clinically detectable microangiopathy. This study investigates the posturally induced change in blood flow to the skin of the foot in prepubertal and postpubertal patients with in sulin dependent diabetes. Laser Doppler fluximetry was used to assess the postural change in blood flow at the pulp of the great toe. Postur al vasoconstriction (dependent flux value/supine flux value x100) was greater after puberty in normal subjects (median (range) 60.4 (7.0-164 .9)% prepubertal v 20.5 (5.9-101.0)% postpubertal). Prepubertal childr en with diabetes did not differ from their healthy peers (69.8 (7.2-19 2.7)% with diabetes v 60.4 (7.0-164.9)% controls); however postpuberta l children with diabetes had a significantly impaired postural vasocon striction (40.6 (7.9-140.2)% with diabetes v 20.5 (5.9-101.7)% control s). Abnormalities in the normal reduction of blood flow on standing oc curred in young postpubertal children with diabetes, most of whom were free of complications.