Exercise training delineates the importance of B-cell dysfunction to the glucose intolerance of human aging
Autor: | Steven E. Kahn, John R. Stratton, Kevin C. Cain, Robert S. Schwartz, Itamar B. Abrass, Gilbert W. Fellingham, Valerie G. Larson, Manuel D. Cerqueira, J. C. Beard |
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Rok vydání: | 1992 |
Předmět: |
Adult
Blood Glucose Aging medicine.medical_specialty Endocrinology Diabetes and Metabolism medicine.medical_treatment Clinical Biochemistry Physical exercise Arginine Biochemistry Running Impaired glucose tolerance Islets of Langerhans Endocrinology Insulin resistance Internal medicine Insulin Secretion Hyperinsulinemia Humans Insulin Medicine Exercise Aged Aged 80 and over Glucose tolerance test medicine.diagnostic_test business.industry Biochemistry (medical) Glucose Tolerance Test Middle Aged medicine.disease Bicycling business Hyperinsulinism Body mass index |
Zdroj: | The Journal of Clinical Endocrinology & Metabolism. 74:1336-1342 |
ISSN: | 1945-7197 0021-972X |
Popis: | Aging has been associated with glucose intolerance, insulin resistance, hyperinsulinemia, and diminished islet B-cell function. The relative contribution of these factors to the aging-associated changes in glucose tolerance has been difficult to discern, particularly so for B-cell function, since insulin sensitivity itself is a determinant of B-cell function and, therefore, comparisons of insulin levels and responses between old and young subjects are difficult. To reduce this effect, we compared B-cell function in 14 healthy older men (aged 61-82 yr; body mass index, 21-30 kg/m2), who were exercise trained for 6 months to improve insulin sensitivity, to that of 11 healthy young men (aged 24-31 yr; body mass index, 19-31 kg/m2), who were also trained. Insulin-glucose interactions were assessed by measuring indices of insulin sensitivity (SI) and glucose effectiveness at zero insulin (GEZI) using Bergman's minimal model. B-Cell function was assessed by determining the acute insulin responses (AIR) to glucose (AIRgluc) and arginine at 3 different glucose levels: fasting, approximately 14 mM, and greater than 28 mM (AIRmax). AIRmax provides a measure of B-cell secretory capacity, while the glucose level at which 50% of AIRmax occurs is termed PG50 and is used to estimate B-cell sensitivity to glucose. The insulin sensitivity and glucose effectiveness at zero insulin of the trained older subjects was similar to that of the trained young [SI: old, 5.1 +/- 0.6; young, 6.5 +/- 0.7 x 10(-5) min-1/pM (mean +/- SEM; P = NS); GEZI: old, 1.3 +/- 0.2; young, 1.7 +/- 0.2 x 10(-2) min (P = NS)]. Under these conditions, the fasting glucose levels (old, 5.4 +/- 0.2; young, 5.1 +/- 0.1 mM) and basal insulin levels (old, 49 +/- 6; young, 63 +/- 11 pM) were also similar in the two groups. AIRgluc values were lower in the exercised elderly (old, 253 +/- 50; young, 543 +/- 101 pM; P = 0.01). This decrease in stimulated insulin release was due solely to a reduction in the AIRmax (old, 1277 +/- 179; young, 2321 +/- 225 pM; P less than 0.005); the PG50 was not different (old, 8.9 +/- 0.4; young, 8.8 +/- 0.2 mM; P = NS). These differences in the older subjects were associated with a reduction in iv glucose tolerance (old, 1.49 +/- 0.15; young, 1.95 +/- 0.13%/min; P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS) |
Databáze: | OpenAIRE |
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