Understanding the Disease
At nine years old, I was Mama’s “big helper”…or so I thought. Since my mother was busy teaching, my regular after-school duty was to help prepare a simple meal when she and Daddy returned home from work.
I don’t really remember much about those meals, except that quite often I baked some sweet biscuits or a cake. I do remember mixing together the measured amounts of butter and sugar. Yummmmm, it tasted so good! I know Mama wouldn’t have been very happy if she had known how many times I tasted that sweet mixture. And I often worried a bit as I ate it. Somewhere I had heard about a sugar disease called…now, what was that called? Sugar die-eye-tis? Or something like that.
Obviously my nine-year-old mind knew nothing about what diabetes really is—though, unfortunately, many nine-year-olds have already lived with the disease since they were small.
Today, many adults do not understand diabetes any better than I did as a child. So let’s take a look at what diabetes really is.
To be accurate, we should call the disease by its full name, diabetes mellitus, to avoid confusion with a much rarer and totally different type of diabetes, called diabetes insipidus. But the average person knows the disease simply as diabetes, and so that is what we will call it in this book.
Diabetes is a lifelong disease in which a person’s body either does not produce enough insulin or cannot make proper use of the insulin which it does produce.
Insulin is a hormone—a chemical which helps to regulate and control certain body functions. Insulin is made by the pancreas, which is a small endocrine gland located just below the stomach. In the pancreas, special beta cells in the areas called the islets of Langerhans secrete insulin directly into the bloodstream. There insulin works to control the amount of glucose in the blood.
Glucose is really just sugar. When your body digests the foods you eat, it changes the carbohydrates (as well as some of the proteins and fats) into glucose. Glucose is your source of energy—the fuel for your body. And glucose is the nourishment for the various cells in the body.
If your body had no insulin—no way of controlling the amount of glucose in the blood—you would be in serious trouble. All the glucose from your dinner would stay in the bloodstream, your blood glucose level would be extremely high after meals, and you would feel very sick. You could even become unconscious. The body cannot cope with such an overload of sugar in the blood all at one time. You would have the condition called hyperglycemia (hyper=excessive; glyc=sugar; emia=blood).
On the other hand, without insulin you would be in an even more dangerous condition a few hours after your meal. If you exercised a lot or if you went too long without food, your blood glucose level would get lower and lower as your body used up the glucose for energy. You would develop the condition known as hypoglycemia—very low blood sugar. That’s exactly what happened to Roger Lee, during his soccer game.
When the amount of glucose in the blood gets too low, many vital body functions are not able to continue. For example, the heart must have energy in order to beat, other muscles must have energy in order to move. The brain cells require sugar in order to function. Without glucose in the blood, the body stops working, just as a car or motorcycle stops when it runs out of gasoline.
The human body has been created with the ability to produce insulin to control the amount of glucose in the blood. Insulin has some very important functions. First, at the time of digestion it helps to change extra glucose into glycogen for storage in the liver and in the muscles. Probably 50-60 percent of the glucose from your meal goes directly into storage.
Another important responsibility of insulin is to signal the body’s cells to take in the glucose for their own nourishment and energy. Insulin also helps in the body’s metabolism of utilization of fat.
With no insulin, or if the insulin is not working properly for some reason, the cells cannot use the glucose they need. It is as if the door to the cells is locked, so they starve while the level of glucose in the blood gets higher and higher. Finally, the kidneys come to the rescue, and start filtering sugar out of the blood and into the urine.
Maybe we could illustrate the diabetic’s lack of insulin this way: Imagine a delivery truck (the blood) brining stocks of food (glucose) to a supermarket, a min-market or other food store (the cells). But the door is always locked, so no one ever unloads the truck to restock the store shelves.
If the store runs completely out of food and does not restock the shelves, it will soon have to close up and go out of business.
If the store is going to stay in business, it will have to find some way of getting food onto the shelves. It will either need to find another way to get supplies into the store or have a locksmith come and find a proper key to unlock the door. Or the store will have to find another source of supplies.
In the case of the body’s cells, they are starving—the “shelves are empty”! If they cannot get a fresh supply of glucose from the blood, either they will die or they will have to find another form of nourishment—something that does not need insulin to help it get into the cells.
Fat is a form of nourishment that can get into the cells without insulin. If there is no carbohydrate stored for energy, the body’s cells break down the fats into fatty acids, and use these for energy. This use of fats does give energy. And it does save the life of the cells (and the person whose cells they are). However, it causes some real trouble in the body. In the chapter on diabetic emergencies, we will take a closer look at the trouble called ketoacidosis.
Furthermore, if the body uses fats for energy, the glucose is still waiting there in the blood, unable to get into the cells. Let’s look again at our illustration of the mini-market. Imagine what would happen if more and more delivery trucks kept coming and parking, but none of them unloaded their food supplies. (Or they unloaded all their supplies right there in the road). Soon there would be a terrible traffic jam on the roads. The police would have to come and send (or tow) some of the trucks away.
In the body, the kidneys act as the police. When the blood gets too loaded with glucose, the kidneys begin to filter out the extra glucose and spill it out into the urine. But if the kidneys are continually overworked with policing the amount of sugar in the blood, they may finally go on strike. And that kidney failure is one of the complications of diabetes that we will look at in the chapter on complications.
As we said earlier, in diabetes, either the body is producing too little insulin or the insulin it does produce is ineffective.
On the surface of the body’s cells, there are special places called receptors where the insulin normally attaches itself. If the insulin is bound to those receptors as it should be, it allows glucose to move from the bloodstream into the cells and be used for energy.
These receptors are sort of like locks into which the delivery man must put the key when he brings food supplies to our supermarket. If these locks are jammed, or out of order, the door cannot open to let the supplies come in. Sometimes the receptors on the body cells become insensitive to the insulin—the locks don’t work—and so the cells cannot receive the glucose that is waiting outside in the bloodstream. The pancreas may be making enough insulin, but with spoiled receptors, the insulin is not effective in doing its work.
Types of Diabetes
There are two main types of diabetes mellitus. For now, let us take just a brief look at these two. Later we will see more similarities and differences between them.
Type I diabetes (also called insulin-dependent diabetes mellitus, or IDDM) occurs when the insulin-producing cells in the body do not function, and they make little or no insulin. If the body does not even produce insulin, the glucose cannot move into the cells. To stay alive, the majority of these people will have to depend on insulin injections for the rest of their lives. Type I is the much less common form of diabetes—only about 10-20 percent of all diabetics are insulin-dependent. This kind of diabetes usually begins in childhood or youth.
Type II diabetes (also called non-insulin-dependent diabetes mellitus, or NIDDM) most often begins in overweight adults who are over the age of 40. With type II diabetes, the pancreas does still produce some insulin. In some cases, the body is simply not making enough insulin. In other cases, however, the body may be making an adequate amount of insulin, but that insulin is no longer effective because the cells’ insulin receptors—the “locks”—are jammed. The pancreas may try to remedy the situation by producing more and more insulin. But if the receptors don’t work, even this may not help.
What causes diabetes? Are you among the one in every 12 people who is a likely candidate for it? Read on and see.