Some Basic Science Underlying the Diabetes Diet

Excerpted from
The Diabetes Diet : Dr. Bernstein's Low-Carbohydrate Solution
By Richard K. Bernstein, M.D.

A variety of physiological factors other than the food you eat can and will affect blood sugars. Some of these, such as exercise and insulin resistance, are obvious and well known. Others are rarely if ever addressed in diabetes diets, but they're crucial if you are to be successful in normalizing your blood sugars. Most of these are in some ways applicable to nondiabetics as well. The pages that follow contain simplified discussions of these phenomena, in order to get you jump-started. For those who want to know more, I've provided the page numbers in Dr. Bernstein's Diabetes Solution where further details can be found).

The Laws of Small Numbers

"Big inputs make big mistakes; small inputs make small mistakes" is an indispensable piece of wisdom for life as well as for diet.

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. As an example, think about traffic. Put a small number of cars and trucks on a given stretch of highway and traffic acts in a predictable fashion: you 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. Nor can you normalize blood sugar unless you can predict the effects of what you're eating on your blood sugars.

If you can't accurately predict your blood sugar levels, then you can't accurately predict your needs for insulin or oral blood sugar-lowering agents. If the kinds of foods you're eating give you consistently unpredictable blood sugar levels, then it will be impossible to normalize blood sugars.

For people who use insulin, the Laws of Small Numbers are absolutely crucial because when you inject insulin, not all of it reaches your bloodstream. The more insulin you use, the greater the level of uncertainty. An unpredictable portion of injected insulin is destroyed by the liver and the immune system. How and where you inject can affect absorption of the commonplace large doses as well. According to researchers at the University of Minnesota, a 20-unit injection in your and will result in an average 39 percent variation in the amount that makes it into the bloodstream from one day to the next. Abdominal injections had a 29 percent average variation.

These are enormous variations. These numbers are averages, remember, so on any given day, your injection of the same amount could be twice or half as effective as the one on the day before. The larger your doses of insulin, the bigger the discrepancy. So if you cat large amounts of carbohydrate that you need to cover with large doses of insulin, your ability to predict your insulin needs is almost nil. If you inject 20 units of insulin at one time, a 29 percent variability will, on average, create a 6-unit discrepancy in your absorption (could be 8 units, could be 4). Since 1 unit lowers a typical 150-pound adult's blood sugar by 40 mg/ dl, the result is, on average, a 240 mg/ dl blood sugar uncertainty (40 mg/ dl x 6 units). The good news is that at doses smaller than 7 insulin units for adults, the absorption uncertainty becomes negligible. This diet enables us to use smaller doses of insulin, keeping unpredictability in check.

Another Law of Small Numbers relates to the fact that in the United States, food manufacturers are permitted an error of plus or minus 20 percent when estimating carbohydrate content on product labels. For a customary 150-gram carbohydrate portion of pasta, this boils down to a typical blood sugar uncertainty of 150 mg/ dl (5 mg/ dl/ gm x 150 gm x 20 percent). For 2 cups of salad containing a total of only 12 grams carbohydrate, the blood sugar uncertainty would be only plus or minus 12 mg/ dl. The uncertainties in food value books may sometimes be double or quadruple those on labels, making high carb values even more risky.

Bottom line: observing the Laws of Small Numbers in counting carbs and, correspondingly, injecting insulin will help you get control of your diabetes or your weight.

Diminished Phase I Insulin Response

The normal blood insulin response to a meal comes in two phases. During the time between meals, your body stores up insulin in order to respond to the next meal. When you eat, phase I is the instant release of stored insulin in response to the "glucose challenge" of the meal you've started to eat, and it prevents a sharp rise in blood sugars. Phase II is slower and longer in duration, and consists of the release of insulin as your body is making it.

In type 1 diabetics both phases of blood insulin response are nonexistent. In type 2 diabetics the first phase is diminished or absent. This is one of the hallmarks of type 2, and the reason blood sugars can rise sharply shortly after beginning a meal. Intramuscular insulin injections approximate the phase II response, but there is no way, medically, to mimic the phase I response. Thus a low-carbohydrate diet, which requires less insulin, is absolutely essential for normalizing blood sugars.

Gluconeogenesis

Gluconeogenesis is essentially Latin for "new creation of glucose." If you were a healthy nondiabetic and hadn't had a meal in 3 days, your blood sugar levels would probably still be essentially within a normal range. Why? The body can convert protein to glucose. This includes protein you cat, but also stored protein—as in your muscles and other tissues, which continually receive amino acids (the "building blocks" of protein) from and return them to the bloodstream. This constant exchange makes amino acids always available for conversion to glucose. So (to simplify) for the nondiabetic, if you haven't eaten, your body senses the drop in blood sugars and converts stored protein to glucose; meanwhile, the normal insulin response keeps blood sugars from going too high.

For the diabetic with a major insulin deficiency, the problem is that insulin response may not be enough to bring blood sugars back into line. So even though you haven't eaten, if you test your blood sugars you'll find they're high. In the old days, before insulin became available for injection, type 1 diabetics were said to melt away into sugar water.

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 too little insulin to offset your insulin resistance. For type 2s, appropriate weight loss and vigorous exercise may be essential to improving your body's sensitivity to insulin.