Altered responses to hypoglycemia of healthy elderly people.

Abstract

Many elderly people are treated with medications or are subjected to diseases which can cause hypoglycemia. We conducted the following studies to assess whether alterations in counterregulatory hormone release, decreased awareness of warning symptoms or alterations in psychomotor performance might increase the susceptibility of the elderly to hypoglycemia. Healthy, nonobese young (n = 10, age < 30) and old (n = 9, age > 65) subjects underwent paired hyperinsulinaemic clamp studies (insulin infusion rate 60 mU/m2.min). In the control study, glucose was kept at 5.0 mmol/L for 5 h. In the hypoglycemic study, glucose was kept at 5 mmol/L for 1 h and was lowered in stepwise fashion to 4.4, 3.8, 3.3, and 2.8 mmol/L in each subsequent hour. Subjects were blinded as to which study they were undergoing. Counterregulatory hormones were measured and a hypoglycemic symptom checklist was administered every 15 min in each study. Neuropsychological tests were performed at regular intervals. The glucose threshold for release of counterregulatory hormones was defined as the glucose level at which the values during the hypoglycemic study first exceeded values during the control study by 2 SD. The glucose threshold for glucagon and epinephrine release was higher in the young (approximately 3.3 mmol/L) than the old (approximately 2.8 mmol/L) and the epinephrine responses to hypoglycemia were also greater in the young. The threshold for release of GH (approximately 3.3 mmol/L) and norepinephrine and cortisol (approximately 2.8 mmol/L) was similar in each age group, as was the magnitude of release of these hormones. Although the variance in symptoms scores was large, the elderly appeared to have reduced awareness of the autonomic but not neuroglycopenic symptoms of hypoglycemia. There was no difference between young and old in the effect of hypoglycemia on neuropsychologic tests. We conclude that healthy elderly people may have impaired release of glucagon and epinephrine in response to hypoglycemia and reduced awareness of the autonomic symptoms of hypoglycemia.

Review of Hypoglycemia in the Older Adult: Clinical Implications and Management

“…Aging has an impact on counter-regulation (5,6). In healthy older adults without diabetes, glucose counter-regulation by glucagon as well as growth hormone and epinephrine responses to hypoglycemia are impaired through the physiology of aging, effectively muting the autonomic process, which would have produced symptoms in the patient (3,5).…”

“…In healthy older adults without diabetes, glucose counter-regulation by glucagon as well as growth hormone and epinephrine responses to hypoglycemia are impaired through the physiology of aging, effectively muting the autonomic process, which would have produced symptoms in the patient (3,5). Glucose is not properly secreted when its levels fall, which represents loss in pancreatic, renal and hepatic processes.…”

Nutrition and Aging: Changes in the Regulation of Energy Metabolism With Aging

“…However, when hypoglycemia occurs, it powerfully elicits sensations of hunger in young adults. In contrast, even healthy older adults have a broader range over which circulating glucose is maintained and in addition have attenuated counterregulatory responses and delayed recovery from hypoglycemia (85,99,100). Melanson et al (95) recently reported persistently elevated postprandial glucose and insulin in the older women following consumption of 2,092-and 4,184-kJ test meals compared with younger women.…”

Practical strategies to normalize hyperglycemia without undue hypoglycemia in type 2 diabetes mellitus

“…Several studies have shown that even though hormonal counterregulation was similar in healthy young and elderly men, elderly men had reduced symptoms at a given hypoglycemia level, suggesting impaired end-organ sensitivity to counterregulatory hormones [ 26 ]. In contrast, other studies found a signifi cant decrease in counterregulatory hormones in healthy elderly men compared with young men, with similar symptom responses [ 27 ]. Healthy elderly subjects also have decreased insulin clearance compared with young, healthy individuals [ 28 ], which may pose a problem in elderly patients using exogenous insulin or secretagogues.…”