Effects of an Oral Glucose Load on Serum Immunoreactive Insulin, Free Fatty Acid, Growth Hormone and Blood Sugar Levels in Young and Elderly Subjects*

Abstract

ABSTRACT In 29 healthy young adults and 22 ambulatory elderly subjects, a study was made of the effects of an oral glucose load on the levels of serum immunoreactive insulin (IRI), free fatty acids (FFA), growth hormone (HGH) and blood glucose. In the elderly, the pre‐load blood glucose and serum IRI levels were higher than in the younger group, reached the peak more gradually, and took longer to return to the baseline values. There was no significant difference in the serum FFA levels between the two groups until 3 hours after the glucose load, at which time the FFA values had returned to the fasting level in the young subjects but remained depressed in the elderly subjects. Serum HGH fasting levels in the elderly males were significantly higher than in the younger males and remained so at 1–2 hours after the glucose load. For the females, the numbers were too small and the intragroup variability too great to permit drawing conclusions. The total findings lend support to Dilman's hypothesis of a genetically programmed elevation of the hypothalamic threshold to feedback suppression, with age.