The effects of repeated insulin hypoglycaemia on capillary and tissue metabolism in man.

Abstract

(1) The response of 2 male schizophrenic patients in terms of quantified extent of mental state disturbance, 12 measures of capillary vascular physiology and oxidative metabolism and 5 estimates of tissue cell metabolism were employed kinetically to determine the influence of insulin hypoglycaemia in man. Longitudinal observations were continued for 5 months, serial measurements being obtained daily prior to commencement of the insulin course and in the afternoons after interruption of the hypoglycaemic state by glucose. (2) Clinically, both patients improved initially but only one of them maintained this improvement and returned to his job; the other was finally committed to an Ontario Hospital. This difference was reflected in a mean fall of 10 points in the quantified disturbance rating scale in the former and of only 3 points in the latter patient. (3) The post-insulin state differed significantly from the pre-insulin baseline state in the patient who improved in that the body weight increased while tissue oedema diminished; the C.F.F. rose; pCO2 was increased; pulse pressure widened; capillary blood pressure fell; arteriolar and capillary blood flow both increased; and capillary oxygen saturation also rose. In the patient who finally failed to improve clinically, similar changes were also found save that although his pO2 increased, arteriolar blood flow fell somewhat and, in general, the physiological gains were less than in the former patient. Improvement in capillary resistance occurred in both patients, but the results could not be analysed statistically. (4) Microscopic observations showed a gain in capillary tone in both patients following the hypoglycaemic episodes, and an increase in translucency in the inter-vascular and peri-vascular tissue field. Together with the decrease in waterlogging of the tissues, it was felt that these findings supported an improved local cellular metabolism. Again, the changes in the clinically indifferent patient were differentially less well marked than in the patient who did well from his treatment.