DEAR DOCTOR K: I have had Type 1 diabetes for 20 years. I'm worried I may get ketoacidosis, even though I never have. How do I protect myself?

DEAR READER: You are at risk for ketoacidosis, but the fact that you've never had it is encouraging. It means you're already doing the things you need to do to prevent it. That's important, because diabetic ketoacidosis is a serious complication of Type 1 diabetes.

Let's start with a few basics. Type 1 diabetes is often called "insulin-requiring" diabetes. It is caused by an attack of your immune system on the cells in your pancreas that make insulin. As a result, you need to take insulin shots to compensate for the insulin your pancreas cannot make.

Why do you need insulin? Insulin allows sugar to leave the blood and enter the cells of your body. The cells are where the sugar is needed because they use it as an energy supply. When your pancreas cannot make enough insulin, sugar stays in your blood since it can't get into your cells. That causes blood sugar levels to rise.

When you don't make enough insulin, your blood also becomes more acidic, mainly because low insulin causes fat in your body to break down into substances called ketones. Ketones are an alternative source of energy for your cells. However, ketones are acids, and they raise the acid level in your blood.

Another reason your blood becomes more acidic in Type 1 diabetes is that the high blood sugar causes you to pass a lot of urine, which then causes you to become dehydrated. Being dehydrated makes it harder for your kidneys to get rid of extra acid.

The symptoms of diabetic ketoacidosis are vomiting, abdominal pain, frequent urination, extreme thirst and dry mouth. Ketoacidosis is always accompanied by dehydration. As blood ketone levels increase, your breathing may become slow and deep, and your breath can have a fruity odor.

If the blood becomes extremely acidic, ketoacidosis can cause falling blood pressure, coma and death.

Ketoacidosis can occur when people with Type 1 diabetes stop taking their insulin injections or if their insulin dose is too low. It can be triggered by an infection or severe physical stress, such as an injury or surgery. Your body can need more insulin than usual when under stress. Ketoacidosis rarely occurs in people with Type 2 diabetes.

Ketoacidosis is treated in the hospital with insulin, fluids given into a vein and potassium supplements.

If you have Type 1 diabetes, you can help prevent diabetic ketoacidosis by taking insulin as directed and following the diet prescribed by your doctor. You should also test your blood glucose regularly. If your blood glucose reading is very high, test your urine for ketones using special paper test strips that you should have at home. Check your blood sugar more frequently if you are sick or under stress.

You can get ketoacidosis, but if you continue to take proper care of yourself, you may never suffer from this potentially serious condition.

Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.

DEAR DOCTOR K: I have had Type 1 diabetes for 20 years. I'm worried I may get ketoacidosis, even though I never have. How do I protect myself?

DEAR READER: You are at risk for ketoacidosis, but the fact that you've never had it is encouraging. It means you're already doing the things you need to do to prevent it. That's important, because diabetic ketoacidosis is a serious complication of Type 1 diabetes.

Let's start with a few basics. Type 1 diabetes is often called "insulin-requiring" diabetes. It is caused by an attack of your immune system on the cells in your pancreas that make insulin. As a result, you need to take insulin shots to compensate for the insulin your pancreas cannot make. Why do you need insulin? Insulin allows sugar to leave the blood and enter the cells of your body. The cells are where the sugar is needed because they use it as an energy supply. When your pancreas cannot make enough insulin, sugar stays in your blood since it can't get into your cells. That causes blood sugar levels to rise.

When you don't make enough insulin, your blood also becomes more acidic, mainly because low insulin causes fat in your body to break down into substances called ketones. Ketones are an alternative source of energy for your cells. However, ketones are acids, and they raise the acid level in your blood. Another reason your blood becomes more acidic in Type 1 diabetes is that the high blood sugar causes you to pass a lot of urine, which then causes you to become dehydrated. Being dehydrated makes it harder for your kidneys to get rid of extra acid.

The symptoms of diabetic ketoacidosis are vomiting, abdominal pain, frequent urination, extreme thirst and dry mouth. Keto-acidosis is always accompanied by dehydration. As blood ketone levels increase, your breathing may become slow and deep, and your breath can have a fruity odor. If the blood becomes extremely acidic, ketoacidosis can cause falling blood pressure, coma and death.

Ketoacidosis can occur when people with Type 1 diabetes stop taking their insulin injections or if their insulin dose is too low. It can be triggered by an infection or severe physical stress, such as an injury or surgery. Your body can need more insulin than usual when under stress. Ketoacidosis rarely occurs in people with Type 2 diabetes. Ketoacidosis is treated in the hospital with insulin, fluids given into a vein and potassium supplements.

If you have Type 1 diabetes, you can help prevent diabetic ketoacidosis by taking insulin as directed and following the diet prescribed by your doctor. You should also test your blood glucose regularly. If your blood glucose reading is very high, test your urine for ketones using special paper test strips that you should have at home. Check your blood sugar more frequently if you are sick or under stress. You can get ketoacidosis, but if you continue to take proper care of yourself, you may never suffer from this potentially serious condition.

Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.