Sometimes,
even when you think you’re doing everything right, your blood
sugars may not respond as you expect. Often this will be due to one
or more of the biologic curiosities that affect diabetics. The purpose
of this chapter is to acquaint you with some real phenomena that can
confound your plans, but which you can frequently circumvent if you
are aware of them.
GLUCONEOGENESIS, THE DAWN
PHENOMENON, AND DELAYED
STOMACH-EMPTYING
You may begin to notice as you regularly monitor your blood sugars
that your fasting blood glucose on waking in the morning is considerably
higher than it was when you went to bed, even though you didn’t
get up for a midnight snack. There are three common causes for this:
gluconeogenesis, the dawn phenomenon, and gastroparesis (delayed stomach-emptying).
Gluconeogenesis
Gluconeogenesis, which we discussed briefly in Chapter 1, is the mechanism
by which the liver (and, to a lesser degree, the kidneys and intestines)
converts amino acids into glucose. Dietary protein is not the only source
of amino acids. The proteins of your muscles and other tissues continually
receive amino acids from and return them to the bloodstream. This constant
flux ensures that amino acids are always available in the blood for
conversion to glucose (gluconeogenesis) by the liver or to protein by
the muscles and vital organs. Some
diabetics still make adequate insulin to prevent gluconeogenesis. However,
once your insulin production drops below a certain level, your liver
(and your kidneys and intestines) will inappropriately produce glucose
and thus raise your blood sugar even while you’re fasting.
In all likelihood, you won’t be able to control this phenomenon
by diet alone, particularly if you’re a type 1 diabetic or a type
2 making far too little insulin to offset your insulin resistance. For
type 2s, appropriate weight loss and vigorous exercise may be the most
help in improving the sensitivity of the liver to whatever insulin remains.
The most reliable treatments will involve medication, either certain
oral agents or insulin. If you’re obese, however, large doses
of insulin can make you more obese and more resistant to insulin. So
a major goal should be to bring your weight into line.
The Dawn Phenomenon
As you know, I’m a type 1 diabetic. I no longer make any insulin
at all. If I decide to fast for 24 hours—eat absolutely nothing—I
will need to inject 3 units of long-acting insulin in the morning to
prevent gluconeogenesis for 18 hours. If I check my blood sugar every
few hours,
it will remain constant, confirming that the insulin is suppressing
gluconeogenesis.
If, 18 hours after my first injection—and while still fasting—I
inject another 3 units of insulin, common sense would maintain that
this second dose should suppress gluconeogenesis overnight.
So I go to sleep and awaken 9–10 hours later. On arising, I check
my blood sugar. Instead of being constant, as it was during my waking
hours, it’s now 20–100 mg/dl higher than it was at bedtime.
If I were to try the same experiment a week later, I’d experience
about the same overnight rise in blood sugar. Why?
Although the mechanics of the dawn phenomenon aren’t yet entirely
clear, research suggests that the liver deactivates more circulating
insulin during the early morning hours than at other times of the day.
It doesn’t matter whether you made the insulin yourself or injected
it;
the liver has no preference. With inadequate circulating insulin to
prevent gluconeogenesis, your blood sugars may be higher in the morning
than they were at bedtime.* This isn’t a problem for a nondiabetic,
because a body with fully functional pancreatic beta cells will just
make more insulin.
Investigators have actually measured blood sugar every hour throughout
the night under similar circumstances. They find that the entire blood
sugar increase occurs about 8–10 hours after bedtime for most
people who are so affected. That doesn’t mean, however, that you
should sleep only 7 hours a night to try to avoid it. Both the time
it takes for blood sugar to increase and the amount of the increase
vary from one person to another. An increase may be negligible in some
and profound in others. This is one of many reasons why any truly
workable program for blood sugar normalization must be tailored to the
individual.
Though it is more apparent in type 1 diabetics, many type 2 diabetics
also show signs of the dawn phenomenon. As you will see, the treatments
described in this book take this phenomenon into account.
*Consuming alcohol at bedtime can inhibit gluconeogenesis overnight,
but not in a predictable fashion.
Gastroparesis
This condition has a chapter all its own (Chapter 22), and we will discuss
it there in detail. However, it’s important to mention it in any
list of factors that can lead to puzzling blood sugar readings.
Most people who’ve had long-standing diabetes develop some degree
of damage to the nerves that govern the muscles of the stomach and intestines.
Gastroparesis diabeticorum (the weak or paralyzed stomach of diabetics)
is caused by many years of elevated blood sugars.
If you’re a type 1, or a type 2 who isn’t making significant
amounts of insulin, it can have unpredictable effects on blood sugar.
Like diabetes itself, gastroparesis can be mild to severe. In extreme
cases, people may walk around for days with constipation, belching,
midchest burning, and bulging stomachs. Much more common, however, is
mild gastroparesis in which physical symptoms are not apparent
but blood sugars are erratic.
The big problems with gastroparesis arise if you’re taking insulin.
If you take your insulin before a meal to cover a rise in blood sugar
but the meal remains in your stomach and glucose doesn’t enter
the bloodstream as predicted, the insulin can take your blood sugar
dangerously low. I know three individuals who experienced daily episodes
of unconsciousness and seizures from time to time after meals for several
years before I met them and diagnosed this condition.
There are, however, ways of controlling blood sugars in spite of the
unpredictability of this condition, and these are discussed in Chapter
22, “Delayed Stomach-Emptying.”
Reprinted from Diabetes Solution New and Revised 2003 Chapter 6
Print
This
 Strange
Biology Part 5
PHENOMENA PECULIAR TO DIABETES THAT CAN AFFECT BLOOD SUGAR
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Strange
Biology Part 4
PHENOMENA PECULIAR TO DIABETES THAT CAN AFFECT BLOOD SUGAR
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Strange
Biology Part 3
PHENOMENA PECULIAR TO DIABETES THAT CAN AFFECT BLOOD SUGAR
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Strange
Biology Part 2
PHENOMENA PECULIAR TO DIABETES THAT CAN AFFECT BLOOD SUGAR
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Strange
Biology Part 1
PHENOMENA PECULIAR TO DIABETES THAT CAN AFFECT BLOOD SUGAR
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We would like to thank the publisher Little Brown and Company and
Dr. Richard K. Bernstein, for allowing us to provide excerpts from Diabetes
Solution.
Copyright © 2003 by Richard K. Bernstein, M.D.
All rights reserved. No part of this book may be reproduced in any form
or by any electronic or mechanical means, including information storage
and retrievalsystems, without permission in writing from the publisher,
except by a reviewer who may quote brief passages in a review.
Author’s Note
This book is not intended as a substitute for professional medical care.
The reader should regularly consult a physician for all health-related
problems and routine care.
