Genes Play a Role

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

(Page 5 of 6)

Many genetic markers for type 1 diabetes have been identified only recently. If a child has genes HLA-DR3 or HLA-DR4 on his sixth chromosome, inherited from both parents, he has 21?2 times more chance of becoming a type 1 diabetic after a viral infection. Eighty-five to 90 percent of all type 1 diabetics have DR3 and/or DR4. And if aspartic acid is not found in position 57 in these genes, the risk of diabetes increases even more. The worst-case scenario is to have both DR3 and DR4. But remember, even if a youngster has DR3 or DR4 genes, it is not inevitable that he or she will develop the disease.

Variants of another HLA gene may also play a role in this kind of diabetes. Researchers have recently found that DQA1 (0301) and DQB1 (0302), again on the sixth chromosome, are strong predictors of diabetes when passed along by two parents. Others - for example, DQB1 (0201) and DQB1 (0602) - are the most protective against it.

A second indicator is the presence of cytoplasmic pancreatic-islet-cell antibodies, found in 80 to 90 percent of children destined to become diabetics. In addition to these antibodies, the presence of genes ILA2 and GAD65 let us know when to start treatment. The likelihood of a child with all three indicators of becoming diabetic is almost 100 percent; with two of the three, it's 80 percent. Tests are currently under way at Columbia Presbyterean Medical Center in New York City to determine whether treating new-onset or recently diagnosed children with the antibody HOKT3Y (Ala-Ala) can preserve their beta cells.

But if, like the Inuits, a child has B7 on the sixth chromosome, his chances of diabetes are decreased. And if he has DR2, it is extremely doubtful he will get diabetes. Though people with DR2 make up a quarter of the population, only a few cases of diabetes have ever been reported among them.

Occasionally, diabetes is the result of another physical condition: pancreatitis, tumors, adrenal imbalance, injury to or removal of the pancreas, or damage caused by one of several drugs.

Double Dose: Type 11/2

Many people, perhaps 5 to 10 percent of all diabetics, do not fit neatly into the categories of type 1 or type 2. Instead, they have characteristics of both varieties. Like type 1, they harbor antibodies that attack the beta cells, reducing their insulin production to little or none. And like type 2, their disease develops slowly as they gradually lose their insulin-producing capability and eventually require insulin. They are usually overweight and have insulin resistance. The standard oral medications are usually not effective with this group, and they often need insulin to bring their sugar level down enough to ward off later complications.

Danger: Prediabetes

Prediabetics are people who have blood glucose levels that are higher than normal but not high enough to qualify them as true diabetics. With a fasting plasma glucose level between 100 mg/dl and 125 mg/dl, they have "impaired glucose tolerance" (IGT) and about half of them will be diagnosed as diabetics within ten years.

If you are in this category, you should be treated as a diabetic because you may already be on your way to its many unpleasant complications such as cardiovascular disease, kidney failure, and vision loss. You can lower your risk of continuing down the path to big trouble by losing weight (if you are too heavy), exercising regularly, cutting back on fats, eating judiciously (see Chapter 3), and maybe even taking an insulin-sensitizing medication (see Chapter 16 for more about stopping diabetes in its tracks).

Who Gets Diabetes?

Diabetes gives geneticists headaches because it is almost impossible to predict, even in the presence of defective genes, who will eventually become diabetic, although many risk factors have recently been determined (see Chapter 16).

It was once thought that all the children of two diabetic parents would eventually become diabetic. Today it is thought that 60 percent is a more accurate figure. With one diabetic parent, sibling, or child, there is a 3 percent chance of diabetes by the age of forty to fifty-nine, a 10 percent chance after sixty.

The identical twin of a person who becomes diabetic before forty has a 30 percent likelihood of developing the disease. If the disease has its onset after forty, the chance an identical twin will have it increases to close to 100 percent, but if the disease does not occur within three years, the identical twin is probably home free. Fraternal twins, by the way, have about the same risk as other family members - about 10 percent.

Everything's Under Control

Diabetes is all about managing sugar. Once you know you are diabetic, you've got a new goal in life: to keep your blood sugar as close to normal as you possibly can. That means, ideally, between 70 mgs percent fasting and 150 mgs after a meal. That's not easy, especially in times of stress when every diabetic's blood sugar runs rampant, but you can stay within that range most of the time if you remember your future depends on it.

For many years, it was thought that this "tight control" was not too important as long as you felt well and functioned normally. Today we know differently.

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.