Includes art: Medical Caduceus
NOTE: If you have any questions for "Ask the Doctor," please send them to the Voice editorial office. The only questions Dr. Wilson will be able to answer are the ones used in this column.
Wesley W. Wilson, MD, has retired as an Internal Medicine practitioner at the
Western Montana Clinic in Missoula, Montana. Dr. Wilson was diagnosed with type
1 diabetes in 1956, during his second year of medical school. He remains interested
and involved in diabetes education for patients and
professionals.
Q: I am a 39-year-old male with type 1 diabetes. What I want to know is where does it come from? I've done some reading, and I know type 2 runs in families, and has to do with being overweight, but I have type 1, and can't find anyone else in my family with it. Where does type 1 diabetes come from? Is there any new information about this?
A: I'll admit that when I read your question, I put it aside and hoped for inspiration. Finally, in that famous medical journal, the Wall Street Journal, I came across an article written by Sharon Begley, titled "DNA's Double Helix Isn't So Golden Now, But Happy 50 Anyway." The article appeared February 28, 2003, and I feel it is an excellent explanation, for the layperson, about the new ways of looking at inheritance and heredity. The article provided a stimulus for me. Here it goes. It is clear that inheritance of type 1 DM as a trait is more complicated than the colors of sweet peas that Gregor Mendel used in his study of inheritance patterns so many years ago. Factors other than Mendelian are involved.
Very active research is underway into the causes and factors that trigger type 1 diabetes. It seems clear type 1 diabetes results from immune destruction of the pancreatic Beta cells by misdirected antibodies. These faulty antibodies are directed against a person's own cells, attacking these host cells as if they were invading viruses or bacteria. Thus they are called "auto antibodies." It seems persons who develop type 1 diabetes have some problem with antibody formation. It appears persons with type 1 are also at increased risk of antibody attack directed against their own thyroid glands. This explains why so many persons with type 1 also have underactive thyroid glands, and must take supplemental thyroid.
Sharon Begley's article in WSJ describes "system biology," a new way of looking at how biologic systems work, and her example was that a gene causing type 1 DM in one extended family seems to work differently in other families--and if that same gene is put into 100 people with a different genetic makeup, perhaps only a few, if any, will develop type 1 diabetes.
One recent study demonstrated some of the inheritance of type 1. The Diabetes Prevention Study, the DPT1, was designed to determine if small doses of insulin, given to persons at very high risk of developing type 1 diabetes, could prevent development of the disease. The study's background was earlier work suggesting some animals (and some humans) could perhaps be prevented from developing diabetes. Candidates for the DPT1 study were close relatives of a known case of type 1 (sibling, children, or grandchildren). These individuals were checked for antibodies against beta cells or insulin, and, if positive, their ability to secrete insulin was measured. If they were antibody-positive, and showed some impairment of insulin secretion, they were considered to be at high risk of developing type 1 diabetes within the year.
They were then either given a low dose of insulin (to "misdirect" any autoimmune attack, not to lower blood sugars) or placebo, and followed carefully.
One of the hypotheses tested in this investigation was that the close relatives of type 1 diabetics would include a higher percentage of "prediabetic" individuals. It turned out such "clumping" was on the order of no more than three or four per hundred family members - far greater than in the general population, but still quite low (far lower than the likelihood of inheriting type 2 diabetes). Type 1 is to some extent hereditary, but still infrequent in most families.
Though the DPT confirmed the increased risk of type 1 "running in families," the administration of insulin to individuals not yet diabetic did not appear to deter the onset of type 1 diabetes. I believe a trial of oral insulin in additional persons at risk of developing type 1 diabetes is still underway. Since only three or four members out of a hundred might develop type 1, it is not surprising that in many families, only one person has type 1 disease.
Now that it is possible to detect persons at high risk of developing diabetes, it may be possible to block the full onset of this disease.
I must
warn you about some of the "facts" that appear in our news media. The Internet
is a valuable source of information about diabetes, but a lot of material there
is not factual. Be careful of the source. Too often, new developments are prematurely
reported as "breakthroughs." Be cautious, and expect that early reports will
have to be confirmed and tested further.
Look up Sharon Begley's article in the Wall Street Journal. Voice of the
Diabetic is to be trusted, as are articles in Diabetes Forecast,
in the Web sites of the American Diabetes Association, the U.S. Centers for
Disease Control (CDC), and
the National Institutes of Health. The Juvenile Diabetes Foundation is another
good source for type 1 diabetes information. (Editor's Note: Diabetes
Self-Management,
published by Rapaport, is another quality source.) I hope this helps. We will
surely know much more in the near future. I take a great deal of hope knowing
it is now possible to identify some persons who are going to develop type 1
diabetes. If we can identify them, we know who to test.