How Is Insulin Used? Type 2

Diabetes Survival Guide: Understanding the Facts About Diagnosis, Treatment, and Prevention
by Stanley Mirsky, M.D., Joan Rattner Heilman

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How Is Insulin Used?

In the normal person, starches, sugars, and proteins (58 percent of which is eventually converted into carbohydrate) are broken down by the intestines into glucose, a form of sugar. The glucose is carried throughout the body by the bloodstream, entering the cells with the help of insulin, then burned for energy by the muscles. Some of the leftovers are stored in the muscle cells or converted into fat. The rest is stockpiled in the liver in the form of glycogen, to be called upon later if the blood sugar falls too low.

If there is not enough insulin or if the insulin available cannot help the glucose permeate the cells, this sugar accumulates in the blood, often in very high concentrations. The result is diabetes.

In a nondiabetic, glucose concentration is usually below 100 milligrams per 100 milliliters of blood plasma, and even after a huge overload of sugar rarely goes above 160 to 180 mgs. In uncontrolled diabetics, it can go much higher, frequently reaching 800 or even 1,000 mgs. Though there's obviously plenty of glucose available to feed the body's hungry tissues, it cannot be used effectively and the cells can literally starve, no matter how much you eat.

At the same time, the liver is stimulated to release its stores of sugar and then to begin a process called gluconeogenesis. In a response to an emergency call for more fuel, this important organ takes the huge amounts of amino acids produced by the starving tissues and changes them into more glucose. Fats are also transported to the liver. Now ketones, the end products of the burning of fat instead of carbohydrate for fuel, also overload the kidneys and spill into the urine. This is called ketoacidosis. When this happens, and nothing is done to remedy the situation, the body lapses into a diabetic coma - a real emergency.

By the way, people who are trying to lose weight on a high-fat diet such as Atkins also produce ketones, but this is not dangerous as long as their blood sugar remains normal. It is only when ketones are combined with high blood sugar that ketoacidosis becomes a problem.

Type 2 (Noninsulin-Dependent Diabetes Mellitus, Or Niddm)

About 92 percent of diabetics are type 2. If you are in this category, you continue to manufacture insulin, perhaps not enough to cover your needs, or perhaps more than enough, but it cannot be efficiently utilized. You can probably control your diabetes with diet and exercise, or diet combined with oral hypoglycemic drugs that stimulate the release of insulin, delay the absorption of carbohydrates, or lower your blood sugar by suppressing the liver's output of glucose. Or you may require insulin injections to supplement your own supply, or the new drugs called incretins to make your available insulin more effective.

Although your diabetes may have been discovered after you developed specific symptoms such as excessive thirst and urination, more likely you were diagnosed during a routine medical checkup. Or maybe your eye doctor or dentist was the first to suspect it. Most cases of type 2 occur gradually, and never present obvious warning signals.

Heredity plays a very important role for type 2s. We know there must be a genetic predisposition, perhaps resulting in early aging of the pancreatic cells or the shutdown of insulin receptors. When some kind of stress - overweight or pregnancy, for example - is added to the genetic tendency, diabetes is the result. The sumo wrestlers of Japan are programmed by their genes to gain tremendous amounts of weight. They are adored by the sportsmen of Japan, but develop diabetes and heart disease early in their lives. They blaze like meteors across the sky, but the trip is short.

The genetically isolated Pima Indians who live in a remote river valley in the Arizona desert tend to be sedentary, overweight, and diabetic. Half of the Pimas over thirty-five have diabetes, 15 times the incidence among the general population in the United States, the highest rate ever recorded. Yet those Pimas who live in Mexico and work the land usually remain thin and do not have evidence of increased diabetes.

Both groups are good examples of the inherited tendencies toward this disease combined with obesity. If you have a family history of diabetes, it would be extremely wise not to get fat.

Even teenagers may have this variety of diabetes (about 5 percent of type 2s are under twenty), more and more of them every year, but statistically it is probably likely to occur in people over forty, becoming more common by age fifty or sixty.

Eighty-five percent of type 2s have a diabetic parent, sibling, or other close relative. Those with an identical twin who is diagnosed with type 2 are almost certain to develop it, too, within a few years.

Copyright © 2006 by Stanley Mirsky. Excerpted by permission of Ballantine Books, a division of Random House, Inc. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.

About the Author

Stanley Mirsky, M.D., is a practicing internist and diabetologist, a past president of the American Diabetes Association of New York State, and a board member of the Joslin Diabetes Center. He was named Endocrinologist of the Year for 2005 by the Mount Sinai School of Medicine. He lives in New York City.

Joan Rattner Heilman is an experienced health writer who has authored hundreds of articles and several books including Estrogen, What Every Woman Should Know: Staying Healthy After 40, and The Complete University Medical Diet. She Lives on Long Island.