Celiac Disease is an autoimmune disease treated with diet alone. Type I diabetes, traditionally called Insulin Dependent Diabetes Mellitus, is an autoimmune disease treated not only with diet but also with injected insulin. An autoimmune disease involves an attack by the individual's immune system on some part of the body.
In Celiac Disease (CD), ingestion of gluten causes the sensitive individual's immune system to attack the tissue of the small intestine. The attack destroys the villi lining the small intestine, which absorb nutrients from food, and results in malabsorption and subsequent medical problems.
The damage usually is not permanent. Once the individual starts a gluten-free diet, the small intestine begins to heal and eventually returns to normal or near normal. The GF diet must be continued for life.
In Type I diabetes, the immune system attacks the insulin-producing beta cells in the islets of Langerhans in the pancreas. The beta cells are destroyed, resulting in a loss of insulin-producing capabilities. Insulin is a vital hormone that permits glucose, a simple sugar that is the body's main source of energy, to enter into and be used by the body's cells to sustain life.
The damage to the islets of Langerhans is permanent. People with Type I diabetes must have injections of insulin for life. These injections are coordinated with the timing and amount of food the individual eats, so diet is a prime concern of the diabetic for life.
The connections between Celiac Disease and Type I diabetes go beyond autoimmunity and diet. Both diseases have genetic and environmental origins. This means an individual is more at risk of developing either problem when a close relative also has it.
On the genetic side, development of one reveals the pre-existing and larger risk that the genes for the other may be present. At least two genes and gene locations are connected with each disease. One gene for each disease is near one gene for the other on the same chromosome. Nearby genes are more likely to pass together to offspring.
However, while the genes are necessary, they are not sufficient to produce the diseases. On the environmental side, researchers know gluten is needed to produce Celiac Disease, but they also know it's not the only environmental cause. With diabetes, the environmental causes are being extensively studied for prevention and cure.
Roughly ten percent of celiacs either have Type I diabetes or might develop Type II diabetes (more later). Estimates differ, but at least five percent of those who have Type I diabetes are or will become celiac. Where the two diseases occur in one individual, in almost all cases, the diabetes is diagnosed first.
Diabetes, which has several forms, is much better known and much more prevalent than Celiac Disease. According to the American Diabetes Association (ADA), eight million Americans have been diagnosed with diabetes. The organization says another eight million have the disease, but have not been diagnosed.
Of the 8 million who are diagnosed, 800,000 are Type I. If at least five percent of those are also celiac, that means there are 40,000 celiacs -- most likely undiagnosed -- among the already-diagnosed diabetic population.
Most cases of Type I are obvious, unlike the more common Type II, which can remain hidden for years.
Type I diabetes is much more serious than CD. Without self-regulating insulin levels, people with Type I walk a tightrope: too low a blood sugar level can lead to potentially deadly "insulin reaction"; too high a blood sugar level can lead to long-term complications that involve the eye, kidney, heart, nerves or vascular system. These complications are minimized with better control of blood sugar.
Often diagnosis of gluten sensitivity in a person with Type I diabetes improves management of the diabetes. As the individual's intestine heals on the gluten-free diet, the rate of food absorption becomes more predictable, and insulin requirements gradually increase as more carbohydrate is absorbed. So it's important that people with diabetes who are also gluten sensitive be properly diagnosed and treated with the gluten-free diet to help them achieve better control of their blood sugar.
Those with diabetes are also at risk for digestive problems that can occur because of nerve damage to the gastrointestinal tract. Called gastroparesis, the damage may involve the intestines, where the nerves that actually wave the villi to move food along can be damaged, and/or the stomach, where the damage can cause incomplete mixing of food, delayed emptying into the small intestine, incomplete absorption of food, nausea and vomiting. Unlike celiac gastrointestinal damage and distress, gastroparesis is not reversible by diet, but may improve with strict control of the blood sugar and some forms of drug treatment. Type I diabetes, which strikes quickly and irreversibly, mostly affects the young; in fact it is sometimes called Juvenile-Onset Diabetes, although it can be diagnosed for the first time in older individuals. Compared to Celiac Disease, which can occur at any age, diagnosis is usually quite easy.
The Type I individual presents with a better defined form of malnourishment than does the celiac: hyperglycemia (high blood sugar), weight loss, extreme thirst, excessive urination laden with unmetabolized sugar and protein, a "fruity" smell to the breath and little or no insulin in the blood. Minimal other damage occurs beyond the destruction of the beta cells.
Normally the islets of Langerhans release insulin into the blood for distribution to nearly all cells in the body. Insulin receptors on the surfaces of cells are activated by the circulating insulin. Once insulin is bound there to its receptor molecule, glucose can enter the cells for the "burning" that produces energy.
Poisons build up quickly within the body in the absence of insulin. Treatment consists of 2-4 subcutaneous injections of insulin a day and control of carbohydrate intake.
The diet all Americans are encouraged to follow today to maintain health and prevent disease is virtually the same as the diet long recommended for people with diabetes to help them control blood sugar levels. Basically, it includes less fat and protein and more carbohydrates than what used to be the standard nutritionally recommended American diet.
The diet features complex, that is less quickly metabolized, carbohydrates to cut down the peak in blood glucose that occurs about two hours after eating. Vegetables, especially starchy ones with fiber for that "complex" factor, and fruit for dessert quickly become staples.
In previous days, people with diabetes were told to avoid sugar. Today the restriction on sugar is indirect. They control (that is measure the intake of) total carbohydrate, adjusting where necessary when they consume direct sugar; usually they eliminate something else that is probably less carbohydrate rich.
The dietary control of Type I diabetes is certainly more of a nuisance than the dietary control of Celiac Disease (although celiacs who have been in situations where there is nothing available to eat might disagree with me). Types and amounts of carbohydrate should be controlled by weighing, estimating portion size or by using food labels.
On the other hand, there is much better information readily available to help those with diabetes monitor what they eat. Food labels provide nearly adequate data to enable the individual to control carbohydrate intake. Relatively inexpensive home-monitoring kits help them keep track of their blood sugar level.
People with Type I diabetes who exercise learn to adjust food and/or insulin to control blood glucose levels. Exercise lowers blood sugar immediately and can continue to influence blood sugar levels for as long as 12 to 24 hours.
So, what about individuals with Type I diabetes who are also gluten sensitive? Their diet is restricted on trace protein (gluten) and controlled on total carbohydrate. In addition to avoiding grains and other foods that contain gluten, they carefully monitor intake of gluten-free carbohydrates. As it does for most celiacs, this leads to reliance on rice and corn.
But celiacs with Type I diabetes also learn to rely on starchy vegetables, like potatoes, winter squash, peas, beets, carrots, onions, and legumes, like black beans, lentils, dried peas, etc. Legumes are especially useful because of their low "glycemic index," which means they raise blood sugar less in proportion to their carbohydrate content than many other foods.
And what about the celiac who is concerned about developing diabetes? By current measure, one in 20 celiacs has Type I diabetes. But unless you're young or have already been diagnosed, your odds of now developing Type I diabetes are very slim.
However, you should be aware of Type II diabetes, a non-autoimmune condition that is usually diagnosed in adulthood. Diagnosed celiacs would have the same risk for Type II diabetes as the general population, which is roughly five percent.
During onset, Type II diabetes, like Celiac Disease, has confusing symptoms, so diagnosis can be missed, creating a greater chance of irreversible damage. Symptoms can include trembling or feeling faint or light-headed two hours after a meal of "sweet" food with a high glycemic index. Others may just feel a lack of energy that drives them to eat more and hence gain more weight -- the classic overeating/underexercising problem.
Once diagnosed, Type II diabetes can sometimes be controlled with weight loss, a very low fat diet, and exercise. Most type IIs take pills; a few need insulin. Long-term complications are the same as those for Type I.
A major but important goal that should be taken on by both the celiac and diabetic communities would be better diagnosis of gluten sensitivity among those with Type I diabetes. In fact, they make up one of the most important high-risk groups that should be screened for gluten sensitivity.
As mentioned, Type I diabetes carries with it the long-term risk of serious complications. Undiagnosed gluten sensitivity ups the ante, not only by playing havoc with blood sugar control but also by adding the usual risks of undiagnosed gluten sensitivity: the possibility of osteoporosis from poor calcium absorption, reproductive concerns, health problems caused by whichever nutrients are malabsorbed and, of course, the increased risk of cancer.
One way diagnosed celiacs can help the diabetes community is by making the connection between the two diseases better known locally. We also need to be especially positive in describing the mechanics of following the diet, the variety of nutritious foods that are absolutely safe, and the feeling of well-being that goes with being gluten-free.
It is important that gluten-sensitive people who also have diabetes not self-diagnose. It's also critically important that their diagnosis include a biopsy. While this is true in general, those with diabetes already face enough health concerns, without adding the burden of misdiagnosis. Initially diabetic celiacs would probably find a dietitian very helpful, although those who have experience in both problems are few and far between. (see box to the right).
And finally, if on a self-serving note, this thought to ponder: Since Type I diabetes gets the respect from the medical community that celiacs long for, we can only hope that more and more diagnosis of CD within the diabetic population will be one very big step toward putting gluten sensitivity on the American health care map. Better health for more people will certainly follow better dissemination of news about gluten sensitivity.
Kemp Randolph, Ph. D., is a science consultant.
Q. What would make a person with Type I diabetes suspect Celiac Disease?
Symptoms would include lactose intolerance, bloating, diarrhea, brittle diabetes, unexplained weight loss, or anemia. However, I would advocate screening all people who have Type I diabetes with the antibodies test at least once.
Q. What would make a celiac suspect Type II diabetes?
This one is harder to suspect. Some signs include getting up to urinate at night, thirst, weight gain, tiredness, vision changes, numbness in the feet, or increased appetite. If there is a family history of Type II diabetes, then the patient should be screened every now and again.
Q. Are there any screening tests for Type II diabetes that a person with Celiac Disease should be aware of?
Yes, fasting blood sugar, blood sugar two hours after a meal, a formal glucose tolerance test and measuring the hemoglobin A1C level. Of these, the last two are the most precise and sensitive.
Q. Should gluten-sensitive children be screened for diabetes and if yes, should the test be repeated from time to time?
This question is much harder to answer. Typically, Type I diabetes has been regarded as an obvious disease that presents suddenly. However, there may be a pre-symptomatic period during which there is damage occurring to the islet cells. If there is also a family history of Type I diabetes, then the family members should be screened.
There is a major project currently underway to study people at risk for Type I diabetes, but no data on studying those with Celiac Disease. The diagnosis of Type I diabetes usually is made first. It is much more uncommon for a diagnosis of Type I diabetes to be made years later in celiac patients already on treatment.
Q. Any additional thoughts?
Work needs to be done to address the question of whether early diagnosis of Celiac Disease may reduce the subsequent risk of another autoimmune disease occurring later in life. One Italian group has reported preliminary work suggesting that may be the case. Also, we don't know about non-Caucasian Type I diabetes and the risk of Celiac Disease.
If you need help managing Celiac Disease and diabetes, you can contact Ms. Marschilok or one of her colleagues at Albany Memorial Hospital in Albany, New York. They will serve as a resource to your local dietitians, or put you in touch with a local dietitian if you need additional help. Call, write or fax: The Diabetes Center at Albany Memorial Hospital, 600 Northern Boulevard, Albany, N.Y. 12204; 518/447- 3500 or 518/447-3504; fax: 518/447-3586. Ask for Katie Marschilok.
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