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medicine at the University of
Texas Health Science Center at
San;Antonio. The true culprit is
compromised hormonal control
of blood glucose levels.
The essential hormones
During the years (up to a decade) that
type 2 diabetes develops, the
hormonal control of blood glucose
breaks down. The four hormones
involved in glucose control are:
Insulin, made in the beta cells
of the pancreas, helps the body
use glucose from food by helping it
to move into the body’s cells. People
with type 2 have slowly dwindling
insulin production and reserves and
increasing insulin resistance.
Amylin, secreted from the beta
cells, slows the release of glucose
into the bloodstream after eating
by slowing stomach-emptying and
increasing the feeling of fullness.
People with type 1 and type 2
diabetes are amylin-de;cient.
Incretins, a group of hormones
secreted from the intestines that
includes glucagon-like peptide 1
(GLP- 1), enhance the body’s release
of insulin after eating. This in turn
slows stomach-emptying, promotes
fullness, delays the release of glucose
into the bloodstream, and prevents
the pancreas from releasing glucagon,
putting less glucose into the blood.
Glucagon, made in the alpha cells
of the pancreas, breaks down glucose
stored in the liver and muscles and
releases it to provide energy when
glucose from food isn’t available.
What’s normal
When diabetes is not present, the
body handles the changing supply of
and demand for glucose (the energy
from food) 24 hours a day. This
system involves the four hormones—
the messengers—and a continuous
feedback loop that moves messages
between the brain, gut, pancreas, and
liver. Here’s how the system works:
When fasting: As blood glucose
falls after peaking from the last
food eaten, the pancreas puts out
less insulin. At the same time, two
other hormones wane: amylin and
glucagon-like peptide 1 (GLP- 1),
which help store and use glucose.
A fourth hormone, glucagon, kicks
into gear to offer a constant ;ow of
glucose. Glucagon sends messages
to the liver and muscles to make
glucose from stored energy.
After eating: Food raises blood
glucose and sends a message to
the intestines to release GLP- 1,
which primes the insulin and amylin
spigots. These hormones help cells
use the glucose from food to fuel
the body. The glucagon spigot
turns off because there’s little need
for glucose from the liver or
muscles when food is available.
The impact of food on blood
glucose, even for a large, high-fat
meal, lasts less than six hours.
During the years type 2 diabetes slowly develops, hormonal control of blood glucose breaks
down. Eventually, here’s what happens during sleep to a person with type 2 diabetes:
Type 2 diabetes during sleep
“Overnight, the liver and muscles get the message
from excess glucagon to ramp up the glucose
supply” because the person is sleeping, not eating,
says Marty Irons, R.Ph., CDE. “There’s not enough
GLP- 1, insulin, or amylin to stem the tide of excess
glucose from the liver and muscles, essentially
throwing this feedback loop out of whack.” High
fasting blood glucose levels,
particularly in the earlier years of
type 2 diabetes, result from this
hormonal imbalance. Evening meals
and snacks may get the blame for morning
highs, but hormones actually deserve it.
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