Background In patients with type I diabetes mellitus, hypoglycemia occ
urs commonly during sleep and is frequently asymptomatic. This raises
the question of whether sleep is associated with reduced counterregula
tory-hormone responses to hypoglycemia. Methods We studied the counter
regulatory-hormone responses to insulin-induced hypoglycemia in eight
adolescent patients with type I diabetes and six age-matched normal su
bjects when they were awake during the day, asleep at night, and awake
at night. In each study, the plasma glucose concentration was stabili
zed for 60 minutes at approximately 100 mg per deciliter (5.6 mmol per
liter) and then reduced to 50 mg per deciliter (2.8 mmol per liter) a
nd maintained at that concentration for 40 minutes. Plasma free insuli
n, epinephrine, norepinephrine, cortisol, and growth hormone were meas
ured frequently during each study. Sleep was monitored by polysomnogra
phy. Results The plasma glucose and free insulin concentrations were s
imilar in both groups during all studies. During the studies when the
subjects were asleep, no one was awakened during the hypoglycemic phas
e, but during the final 30 minutes of the studies when the subjects we
re awake both the patients with diabetes and the normal subjects had s
ymptoms of hypoglycemia. In the patients with diabetes, plasma epineph
rine responses to hypoglycemia were blunted when they were asleep (mea
n [+/-SE] peak plasma epinephrine concentration, 70+/-14 pg per millil
iter [382+/-76 pmol per liter]; P=0.3 for the comparison with base lin
e), as compared with when they were awake during the day or night (238
+/-39 pg per milliliter [1299+/-213 pmol per liter], P=0.004 for the c
omparison with base line, and 296+/-60 pg per milliliter [1616+/-327 p
mol per liter], P=0.004, respectively). The patients' plasma norepinep
hrine responses were also reduced during sleep, whereas their plasma c
ortisol concentrations did not increase and their plasma growth hormon
e concentrations increased, slightly. The patterns of counterregulator
y-hormone responses in the normal subjects were similar. Conclusions S
leep impairs counterregulatory-hormone responses to hypoglycemia in pa
tients with diabetes and normal subject. (C) 1998, Massachusetts Medic
al Society.