Chapter
7: The Laws of Small Numbers /
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"Big inputs
make big mistakes; small inputs make small mistakes."
That is the first thing
my friend Kanji Ishikawa says to himself each morning
on arising. It is his mantra, the single most important
thing he knows about diabetes.
Kanji is the oldest surviving
Type I diabetic in Japan (he is, by the way, younger
than I, but afflicted with numerous long-term diabetic
complications because of many years of uncontrolled
blood sugars).
Many biological and mechanical
systems respond in a predictable way to small inputs
but in a chaotic and considerably less predictable
way to large inputs. Consider for a moment traffic.
Put a small number of automobiles on a given stretch
of highway, and traffic acts in a predictable fashion:
cars can maintain speed, enter and merge into open
spaces, and exit with a minimum of danger. There's
room for error. Double the number of cars, and the
risks don't just double, they increase geometrically.
Triple or quadruple the number of cars, and the unpredictability
of a safe trip increases exponentially.
The name of the game for
the diabetic in achieving blood sugar normalization
is predictability. It's very difficult to use medications
safely unless you can predict the effect they'll have.
You can't normalize blood sugar unless you can predict
the effects of what you're eating.
If you can't accurately
predict your blood sugar levels, then you can't accurately
predict your insulin needs. If the kinds of foods
you're eating give you continuously unpredictable
blood sugar levels, then it will be impossible to
normalize blood sugars.
One of the prime intents
of this book is to give you the information you need
to learn how to predict your blood sugar levels, and
to learn how to ensure that your predictions will
be accurate. Here the Laws of Small Numbers are exceedingly
important.
Predictability. How do
you achieve it?
The Law of Carbohydrate
Estimation
The old ADA dietary
recommendations allowed 150 grams of carbohydrate
per meal. This, as you may know by now, is grossly
excessive. Here is one reason why.
Typically, 150 grams of
carbohydrate would be a good-sized bowl of cooked
pasta. Let's say that you're a whiz at estimating
the amount of carbohydrate in the pasta and can usually
estimate it to within 20 percent from one day to the
next. Twenty percent of 150 grams is 30 grams of carbohydrate.
Now, if you're a nonobese Type I diabetic who makes
no insulin, 1 gram of carbohydrate will raise your
blood sugars by about 5 mg/dl. So, even with your
finely tuned ability to "guesstimate" the
amount of carbohydrate, your blood sugar is off by
a whopping ±150 mg/dl for just this one meal. If your
target blood sugar level is approximately 85 mg/dl,
you've now got a blood glucose level of 235 mg/dl,
or, alternately, 0 mg/dl. Either situation is clearly
unacceptable. If a 20 percent margin of error is your
average, then there will be some days you're off by
only 10 percent, but others when you're off by 30
percent.
Let's try another example.
Say you're a Type II diabetic, obese, and make some
insulin of your own but also inject insulin. You've
found that 1 gram of carbohydrate only raises your
blood sugar by 3 mg/dl. Your blood sugar would be
off by ±90 mg/dl. If your target blood sugar value
is, say, 90 mg/dl, you're looking at a postmeal blood
sugar level of anywhere from 180 mg/dl to 0 mg/dl.
That's the chief problem
with the old ADA diet. Big inputs. But if you can
eat food that will affect your blood sugar by one-tenth
of that margin of error, then you're going to have
a much simpler time of normalizing blood sugar levels.
My diet plan, which we will get into in Chapters 9–11,
aims to keep these margins in the realm of about 10–20
mg/dl. How do we accomplish this? Small inputs.
Eating only a half-cup
of pasta is not the answer. Even small amounts of
some carbohydrate can cause big swings in blood sugar.
And anyway, who would feel satisfied after a meal
of a half-cup of pasta? The key is to eat foods that
will affect your blood sugar in a very small way.
Small inputs, small mistakes.
Sounds so simple and straightforward, so elegant,
it may make you want to ask why no one has told you
about it before.
Say that instead of eating
pasta as the carbohydrate portion of your meal, you
eat salad. If you estimate 2 cups of salad at 12 grams
of carbohydrate and are off not by your usual 20 percent
but by 30 percent, that's still only four grams of
carbohydrate—a maximum potential 20 mg/dl rise or
fall in blood sugar. A bowl of pasta for a couple
of cups of salad? Not much of a trade, you may say.
Well, we don't intend that you starve. As you decrease
the amount of fast-acting carbohydrate you eat, you
can often simultaneously increase the amount of protein
you eat. Protein can, as you may recall, also cause
a blood sugar rise, but this takes place much more
slowly, to a much smaller degree, and is more easily
prevented with medication.
In theory, you could weigh
everything you eat right down to the last gram and
make your calculations based on information provided
by the manufacturer or derived from some of the books
we use. Still, there are problems with that approach.
Say you weigh dried pasta—the manufacturer's estimate
of how much carbohydrate exists in a serving is exactly
that, an estimate, with a margin for error. The Food
and Drug Administration allows for a margin of error
in labeling. And there are other variables—some pastas
are made with egg yolks and wheat flour, some with
water and durum semolina flour. If the manufacturer's
estimate proves to be off by 20 percent, and then
your estimate is off by 20 percent, you're in a realm
of complete unknown. You will have only a vague idea
of what you're actually consuming, and of the effect
it will have on blood sugar.
The idea here is to stick
with low levels of carbohydrates. In addition, stick
with foods that will make you feel satisfied without
causing huge swings in blood sugar. Simple.
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