Reduced Glucose Tolerance in Elderly Human Subjects

Abstract

The high incidence of “abnormal” oral glucose tolerance tests in “normal” subjects over seventy years of age has been confirmed: 77 per cent in this series of individuals. Calculation of glucose disposal rates (GDR's) after three successive intravenous injections of glucose (25 gm.) in fifteen elderly normal subjects revealed GDR's which rose with successive injections, and which were significantly inferior to those observed in young adult normal subjects, yet significantly superior to the findings in patients with tolbutamide-responsive diabetes mellitus. Serum levels of insulin-like activity (ILA) assayed on the rat epididymal fat pad were higher in the elderly than in the young normal subjects both in the fasting state and after the first and third glucose injections. It is concluded that the abnormal tolerance of elderly subjects to an oral load of glucose is not due to retarded absorption of the administered glucose nor to impaired pancreatic secretion of insulin, but presumably results from a higher level of circulating insulin antagonist or from some other cause of delayed glucose uptake from the plasma. The present difficulties in diagnosing diabetes in elderly subjects have been pointed out, and possible means of differentiating between normal and diabetic individuals at all ages have been discussed.