Effect of age and obesity on fasting levels of glucose, insulin, glucagon, and growth hormone in man.

The influence of age and obesity on glucose homeostasis may be mediated via changes in basal levels of the main glucoregulatory hormones, insulin, glucagon, and growth hormone. Fasting plasma levels of these hormones and of glucose were measured in 186 normal male volunteers, 23 to 93 years old. Obesity was assessed as obesity index and by a more accurate anthropometric method as percentage of fat. Age and obesity index had a significant but low linear correlation (r = -.16, p less than .05). Age was not significantly correlated to any other metabolic variable. Percentage of fat was, however, significantly related to the fasting plasma levels of glucose (r = .27, p less than .001), insulin (r = .26, p less than .01), and glucagon (r = .16 less than .05). Fasting glucose was significantly correlated to insulin (r = .30 , p less than .001). These significant correlations persisted when age was held constant. In the basal state the main glucoregulatory hormones are not influenced by age, but plasma glucose, insulin, and glucagon levels are influenced by obesity.