PLASMA INSULIN AND GROWTH HORMONE DURING 22-HOUR FASTS AND AFTER GRADED GLUCOSE LOADS IN SIX HEALTHY ADULTS

SUMMARY Plasma insulin and growth hormone were measured by radioimmunoassay in healthy adults during the latter part of 22 hr. fasts and after graded glucose loads. The insulin concentration was less than 8 μ-u./ml. in all fasting samples and in samples taken after the blood glucose had returned to fasting levels. Insulin levels increased with increasing glucose loads. During fasting, growth hormone showed intermittently raised secretion; in some subjects high values were reached at times which could not be related to external events or to stress. Growth hormone levels were consistently low during the absorption of glucose but rose immediately thereafter. This rise occurred increasingly late and reached increasing levels as the glucose loads were made progressively larger. Insulin had almost invariably returned to fasting levels before the growth hormone concentrations began to rise.