INSTABILITY OF CEREBRAL BLOOD-FLOW IN INSULIN-DEPENDENT DIABETICS

Cerebral blood-flow (CBF) was measured in 23 insulin-dependent diabetics before and 2-3 h after insulin/breakfast. In 10 of these patients CBF changed significantly during the day, with a significant fall in 9. In 3 patients who had the greatest falls in CBF there was a concomitant sensation of an impending faint. Thus CBF is unstable in insulin-dependent diabetics in contrast to control subjects in whom there is little or no variation. Sudden falls in CBF in insulin-dependent diabetics may explain the symptoms of impending faint without hypoglycæmia; such falls would also be relevant to the pathogenesis of strokes in these patients.