What exactly is diabetes?

By David Khorram, MD

I was just told that I have diabetes, but I don’t really understand what it is. I know that it has something to do with blood sugar, but I’m not sure what.

FUEL: THE ROLE OF GLUCOSE

At a very basic level, diabetes is a fuel problem. Just like a car, your body needs fuel to run. The fuel that your body uses comes from the food that you eat. Of course, your body can’t use the food that you eat the way it is. Your body has to break it down—“digest” it. When you eat food, much of it is changed by your body into a form of sugar called glucose. This is the body’s main source of fuel. This fuel, glucose, is moved through the body in the blood stream. But it can’t really be used in the blood stream. It has to get out of the blood stream and into the cells of the body. Each cell then uses the glucose as fuel. For example, in a muscle cell, the glucose is used to make the muscle move. In a brain cell the glucose is used to allow the brain to think. If the glucose is going to be used, it has to get out of the blood and into the cells.

INSULIN: GETTING GLUCOSE WHERE IT NEEDS TO BE

But here’s the challenge. Glucose can’t get into the cells by itself. Each cell has a wall around it. I like to imagine that the wall has lots of doors on it, but something is needed to open the doors and allow the glucose to go into the cell where it will be used. The thing that lets the glucose into the cell is insulin. Insulin is naturally produced by your body in the pancreas. I think of insulin as the thing that opens the doors on the cell wall.

So these are the basics of your body’s energy use. You eat food. The food is changed into glucose. The glucose enters the blood. Insulin is made by your body to transport the glucose out of the blood and into the cells. Inside each cell, the glucose is used as fuel so that each cell can do its job. This is the way things normally go.

This is the normal condition. But what is diabetes? Diabetes is the disease that occurs when glucose cannot enter the cells. You eat the food. Your body turns it into glucose. But in diabetes, glucose cannot get into the cells. So it ends up stuck in the blood stream.

INSULIN PROBLEMS AND HIGH GLUCOSE

“Hmmmm,” you say, “Isn’t insulin the thing that is in charge of getting the doors open so that the glucose can into the cells?” Yes, it is! “So,” you say, “If the glucose cannot get into the cells, there must be some problem involving insulin.” You are exactly right! There are a couple of possible problems involving insulin that lead to high glucose in the blood. One problem can be that the body just isn’t making enough insulin—not enough insulin to open all those doors. And if there isn’t enough insulin to let the glucose into the cells, the glucose is going to pile up in the blood. Another problem can be that the cells aren’t responding as they should to the insulin that is there. It’s like the doors are stuck, or the insulin cannot get the doors open and so, again, the glucose cannot make its way into the cells, and it accumulates in the blood. With both of these problems, the result is that the glucose in the blood gets high. And this is the main problem of diabetes—too much glucose in the blood, or what is often called “high blood sugar.”

ARE YOU WAKING UP A LOT AT NIGHT?

One of the things that happens as all this glucose builds up in the blood is that it starts to leave the body. How’s it going to get out? Some of the high glucose leaves the body through the urine. The body starts to make more urine to get rid of all that extra glucose in the blood. So what happens? Since you’re making all this extra urine, and all this extra water is leaving your body as urine, you get thirsty a lot more and have to drink a lot more water. This is why one of the first things that people with diabetes notice is that they have to pee a lot and they get thirsty a lot. If you’re waking up in the middle of the night to pee more than usual, it could be a sign of diabetes.

HIGH GLUCOSE CAUSES DAMAGE

On the long term, it’s the high glucose in the blood that causes most of the damage that comes from diabetes. The high blood glucose causes damage to the small blood vessels all over the body. In this way, high blood sugar leads to almost all the complications that come from diabetes—the eye damage, the foot damage, kidney damage, heart damage, strokes, poor sexual function.
And this is why controlling the blood glucose is so important: the higher the blood glucose, the more the damage to the blood vessels.

SUMMARY

So, that’s what diabetes is—it’s a problem with glucose getting into the cells of the body. Glucose comes from the food we eat. When the glucose can’t get into the cells, the glucose in the blood goes up, and causes damage to blood vessels all over the body, leading to most of the complications we see in diabetes. The more food we eat, the higher our glucose will be.

Often people get a little confused because blood glucose is called blood “sugar.” When they measure their blood sugar, it might be high, but they haven’t eaten any sugar! Next time, I’ll clear up this confusion and talk about what causes diabetes.

(David Khorram, MD is a board certified physician, public speaker, and a Life and Style columnist for the Saipan Tribune. Questions and comments are welcome. Email davidkhorram@hotmail.com. Copyright © 2004 David Khorram. )