TY - JOUR
T1 - Insulin and glucagon in prevention of hypoglycemia during exercise in humans
AU - Hirsch, I. B.
AU - Marker, J. C.
AU - Smith, L. J.
AU - Spina, R. J.
AU - Parvin, C. A.
AU - Holloszy, J. O.
AU - Cryer, P. E.
PY - 1991
Y1 - 1991
N2 - To assess the roles of decrements in insulin and increments in glucagon in the prevention of hypoglycemia during moderate exercise (~60% peak O2 consumption for 60 min), normal young men were studied during somatostatin infusions with insulin and glucagon infused to 1) hold insulin and glucagon levels constant, 2) decrease insulin, 3) increase glucagon, and 4) decrease insulin and increase glucagon during exercise. In contrast to a comparison study (saline infusion), when insulin and glucagon were held constant, glucose production did not increase and plasma glucose decreased from 5.5 ± 0.2 to 3.4 ± 0.2 mmol/l (P < 0.001) initially during exercise. Notably, plasma glucose then plateaued and was 3.3 ± 0.2 mmol/l at the end of exercise. This decrease was at most only delayed when either insulin was decreased or glucagon was increased independently. However, when insulin was decreased and glucagon was increased simultaneously, there was an initial increase in glucose production, and the glucose level was 4.5 ± 0.2 mmol/l at 60 min, a value not different from that in the comparison study. Thus we conclude that both decrements in insulin and increments in glucagon play important roles in the prevention of hypoglycemia during exercise and do so by signaling increments in glucose production. However, since hypoglycemia did not develop during exercise when changes in insulin and glucagon were prevented, an additional counterregulatory factor, such as epinephrine, must be involved in the prevention of hypoglycemia during exercise, at least when the primary factors, insulin and glucagon, are inoperative.
AB - To assess the roles of decrements in insulin and increments in glucagon in the prevention of hypoglycemia during moderate exercise (~60% peak O2 consumption for 60 min), normal young men were studied during somatostatin infusions with insulin and glucagon infused to 1) hold insulin and glucagon levels constant, 2) decrease insulin, 3) increase glucagon, and 4) decrease insulin and increase glucagon during exercise. In contrast to a comparison study (saline infusion), when insulin and glucagon were held constant, glucose production did not increase and plasma glucose decreased from 5.5 ± 0.2 to 3.4 ± 0.2 mmol/l (P < 0.001) initially during exercise. Notably, plasma glucose then plateaued and was 3.3 ± 0.2 mmol/l at the end of exercise. This decrease was at most only delayed when either insulin was decreased or glucagon was increased independently. However, when insulin was decreased and glucagon was increased simultaneously, there was an initial increase in glucose production, and the glucose level was 4.5 ± 0.2 mmol/l at 60 min, a value not different from that in the comparison study. Thus we conclude that both decrements in insulin and increments in glucagon play important roles in the prevention of hypoglycemia during exercise and do so by signaling increments in glucose production. However, since hypoglycemia did not develop during exercise when changes in insulin and glucagon were prevented, an additional counterregulatory factor, such as epinephrine, must be involved in the prevention of hypoglycemia during exercise, at least when the primary factors, insulin and glucagon, are inoperative.
KW - Catecholamines
KW - Cycle exercise
KW - Epinephrine
KW - Glucose counterregulation
KW - Norepinephrine
KW - Somatostatin
UR - http://www.scopus.com/inward/record.url?scp=0025798969&partnerID=8YFLogxK
U2 - 10.1152/ajpendo.1991.260.5.e695
DO - 10.1152/ajpendo.1991.260.5.e695
M3 - Article
C2 - 2035626
AN - SCOPUS:0025798969
SN - 0002-9513
VL - 260
SP - E695-E704
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
IS - 5 23-5
ER -