Age‐Related Insulin Patterns in Normal Glucose Tolerance*

Abstract

In 707 non-obese female adults with unimpaired glucose tolerance, the fasting blood glucose levels of those in the fourth, fifth and sixth decades of life exceeded the levels found in those of the third decade (20-29 years), but there was no evidence of a progressive increase in successive age decades. The slightly greater fasting glycemia in the later age decades was accompanied by higher increments in blood glucose in the first half hour of the glucose tolerance test. These higher levels of glucose during the fasting state and in the first half hour after oral administration of glucose were not associated with increments in serum insulin greater than those recorded for the third age decade. This age-related increase in fasting and post-glucose blood sugar levels without an increase in serum insulin could result from the age-related increase in the thickness of capillary basement membranes. The higher levels of glucose could then serve to restore glucose transport and cell glucose metabolites to normal without evoking a rise in serum insulin.In 479 obese women with unimpaired glucose tolerance, there was no evidence of the age-related increase in fasting blood glucose nor the slightly exaggerated hyperglycemia found early in the test in non-obese subjects with normal glucose tolerance. The relative fasting hyperinsulinemia and the increased insulin responses to induced hyperglycemia known to characterize obese persons were present in all age decades but the hyperinsulinemia was less marked in subjects older than 30. In these obese subjects with unimpaired glucose tolerance, there was no evidence of any delay in the insulin response to the induced hyperglycemia.In a previous study (1), we observed that in older non-obese females with unimpaired glucose tolerance there was a slightly higher concentration of fasting blood glucose and a slightly greater blood glucose response without 1na a concomitant increase in the serum insulin level. In the studies reported here, we characterize the glucose and insulin patterns for successive age decades in both non-obese and obese women. Detailed analyses of the data indicate that, within the range of normal glucose tolerance, only minor age-related differences are evident in the blood sugar and insulin responses to orally administered carbohydrate. However, the many incompletely defined aspects of aging and of obesity warrant citation of even slight differences which are lost when such data are pooled solely on the basi~of age or body weight.

The effect of ageing on insulin sensitivity and insulin secretion in non-obese healthy subjects

“…It is generally accepted that glucose tolerance de¬ teriorates with advancing age (Nilsson et al 1964;Hayner et al 1965;O'Sullivan et al 1971;Schreuder 1972;Nolan et al 1973;Ratzmann 1973a,b;O'Sullivan 1974;Dudl & Ensinck 1977). The cause of declining glucose tolerance with age is not yet clear (Reaven 1977).…”

Mechanisms of Insulin Resistance in Aging

“…Most studies have demonstrated normal or increased insulin secretion as a function of aging following an oral or intravenous glucose load (3)(4)(5)(6)(7) Subjects. The study group consisted of 44 nonobese subjects.…”

Growth Hormone Levels in Chemical Diabetes

“…Obesity in these female subjects represented a body weight of 146 pounds or more. Our previously published data (12) indicated that glucose tolerance findings in subjects with a body weight between 146 and 180 pounds resemble those in subjects with a body weight greater than 180 pounds.…”