American Diabetes Association Complete Guide to Diabetes: The Ultimate Home Reference from the Diabetes Experts


Type 1 Diabetes

• Early Symptoms and Tests

• Causes and Risk Factors

• Prevention

• Management and Treatments

Now, that you’ve brushed up on some of the basics of diabetes and glucose, you’re probably wondering about your specific type of diabetes. In this chapter, you’ll find out all about type 1 diabetes.

Type 1 diabetes used to be called juvenile diabetes. Half of all people with type 1 diabetes are diagnosed during childhood or their early teen years.

As you know, being diagnosed with diabetes can be a scary—no matter how old you are when you find out. However, being diagnosed with type 1 diabetes as a child can be downright terrifying. For example, it might have come on so fast that you went into a coma before anyone suspected diabetes. After asthma, type 1 diabetes is the second most common chronic disease in children.

Keep in mind, type 1 diabetes can occur at any age. About 5% of adults with diabetes have type 1 diabetes.

Early Symptoms and Tests

People with type 1 diabetes make very little or no insulin, which means that the symptoms of diabetes are often serious and swift. Without insulin, the cells in your body can’t do their essential work. Most people with type 1 diabetes will feel quite sick and may even be rushed to the hospital due to high blood glucose.

Common Symptoms of Type 1 Diabetes

• Frequent urination as the body tries to flush out excess glucose in the blood

• Extreme thirst due to dehydration

• Fatigue because the necessary glucose is not getting to your cells

• Blurred vision because of a buildup of fluid in your eyes or elevated glucose levels

• Weight loss, even with increased appetite

• Nausea and vomiting

A Different Type 1 Diabetes

Some people with type 1 diabetes may have a slow and relentless progression of symptoms. In fact, they may not need to start insulin right away. This condition is called latent autoimmune diabetes of the adult (LADA). As its name suggests, it occurs in adults. Scientists are still trying to clearly define the disorder to improve diagnosis and treatment of people with LADA.

Tests for Type 1 Diabetes

If your doctor suspects diabetes, he or she will perform a blood test, such as the A1C, fasting plasma glucose test, or the random plasma glucose test. These tests are discussed in more detail in chapter 2. If a fasting plasma glucose test is 126 mg/dl or higher or the random plasma glucose test is 200 mg/dl or higher, you may be diagnosed with diabetes.

Your own description of the way your diabetes symptoms developed will help your health care provider classify your diabetes as type 1.

Your health care provider may also take a urine sample to check for the presence of ketones. Ketones are byproducts produced by the body when it breaks down fat for energy. The presence of ketones could be a clue that you have type 1 diabetes. However, keep in mind that ketones are also common in people with type 2 diabetes who are under stress or who have a medical emergency.

In addition, once diabetes has been diagnosed, your health care provider may take a blood sample to test for the presence of autoantibodies in your blood (see more about autoantibodies in the next section). The presence of autoantibodies could mean you have type 1 diabetes. However, some people with type 1 diabetes do not have autoantibodies.

Another measurement, called the “C-peptide” test, measures the amount of insulin produced by the body. It may be ordered if you’ve just been diagnosed with diabetes and is sometimes ordered in conjunction with a diagnosis of type 1 diabetes.

Causes and Risk Factors

Scientists do not know the exact cause of type 1 diabetes. They suspect that it is a combination of factors due to a person’s genetics and environment.

However, scientists do know that in people with type 1 diabetes, their immune system mistakenly destroys the insulin-producing cells of their pancreas. The destruction can happen over months and years. The body treats these insulin-producing cells as foreign invaders (not good!). This is called an autoimmune response.


In fact, the body creates specific proteins called autoantibodies. When certain autoantibodies are present, they indicate an autoimmune response is helping to kill cells in the pancreas.

Four antibodies are particularly common in people with type 1 diabetes: islet cell autoantibodies, insulin autoantibodies, glutamic acid decarboxylase autoantibodies, and tyrosine phosphatase autoantibodies. Doctors often test for the presence of these autoantibodies to determine whether someone has type 1 diabetes.

Autoimmune responses can occur in other diseases, such as multiple sclerosis and lupus. In fact, people with other autoimmune disease, such as thyroid disease and celiac disease, are more likely to have type 1 diabetes.

Scientists do not know what causes autoimmune diseases. However, in diabetes, researchers have found a few triggers that may point to why the body starts attacking itself.

Celiac Disease

One in 20 people with type 1 diabetes has celiac disease.

Genes and Family History

Scientists have long suspected that family history and genes play a role in type 1 diabetes. For example, if your parent or sibling has diabetes, you are more likely to develop the disease than someone without a family history.

The way in which genes interact to cause diabetes is an extremely complex process that scientists are only just beginning to unravel. Some of the most promising discoveries have been made with a group of genes called HLA that are involved in the body’s immune response. Scientists can test a person’s DNA for specific mutations in HLA genes that would indicate that that person might get type 1 diabetes.

Race and Ethnicity

In addition to family history, race and ethnicity appear to play a role in who develops type 1 diabetes. White people are much more likely to develop type 1 diabetes than other racial groups. For example, 1 in 100,000 people in Shanghai, China, has type 1 diabetes, but more than 35 in 100,000 people in Finland have type 1 diabetes. Most likely, certain racial groups pass down genes that either trigger or protect against type 1 diabetes.


Many scientists suspect that viruses may cause type 1 diabetes. Some people who develop diabetes have often had a recent viral infection. Also, cases of diabetes have frequently occurred after viral epidemics. Viruses—such as those that cause mumps, German measles, and a virus related to the one that causes polio—may play some role in causing type 1 diabetes. Nonetheless, there is no virus known that specifically triggers type 1 diabetes.

Chemicals and Drugs

Several chemicals, in rare cases, have been shown to trigger diabetes. Pyriminil, a poison used to kill rats, can trigger type 1 diabetes. Two prescription drugs, pentamidine (used to treat pneumonia) and L-asparaginase (an anticancer drug) can also cause type 1 diabetes.


There is no way to prevent type 1 diabetes. However, scientists are deeply interested in finding ways to delay or reduce the severity of type 1 diabetes.

People without outward symptoms of type 1 diabetes often produce autoantibodies that can be detected in the blood. The autoantibodies may be present several years before diabetes is diagnosed. Currently, scientists can screen people who may be at high risk because they have a family member with type 1 diabetes or because they carry mutations in certain HLA genes.

For example, if you have a parent or sibling with type 1 diabetes, you are 10% more likely to get diabetes. However, if you also carry certain HLA genes or autoantibodies in your blood, you are even more likely to get type 1 diabetes.

Several studies currently underway are testing whether treating these people early may improve their lives. One study is treating people with insulin in a pill form, and other studies are examining whether certain diets could affect the development of type 1 diabetes. Still other studies are aimed at vaccines to slow the progression of diabetes after diagnosis.

In summary, it is unlikely that either genetics or environment alone causes diabetes. Instead, it is probably a complicated interplay between the genes you were born with and the world in which you live.

Management and Treatments

How you manage your diabetes depends on your personal goals and needs. No two people with diabetes are exactly alike. Therefore, everyone with diabetes needs an individualized diabetes care plan.

Common Goals for People with Diabetes

• Prevent short-term problems, such as a glucose level that is too low or too high.

• Prevent or delay long-term health problems, such as heart disease and damage to the nerves, kidneys, and eyes.

• Maintain a healthy lifestyle and keep doing enjoyable activities, such as exercising, working, and socializing.

Work with your health care providers to come up with a plan for managing your diabetes and meeting your goals. You’ll find more about this topic in chapter 9. For now, though, let’s talk about some of the treatments for managing type 1 diabetes.

• People with type 1 diabetes must take insulin. Therefore insulin injections play a big role in your diabetes care plan. How much insulin you need to take depends on your blood glucose level or what you predict the level will be after a meal.

• Naturally, certain food choices also play an important role in your diabetes management plan, because they can add glucose to your blood.

• Usually, exercise can lower your blood glucose level and, in turn, decrease your dose of insulin. So, you’ll need to account for exercise and physical activity in your diabetes management.


Most people with type 1 diabetes take insulin by injecting it with a needle and syringe or an insulin pen. The goal is to mimic normal insulin release as closely as possible.

People without diabetes have a low level of insulin available in the blood most of the time. This is a background, or basal, level of insulin. After meals, a bolus (extra dose) of insulin is released, just enough to clear the glucose in the blood after eating.

To imitate this sequence, you can develop a regular schedule of insulin injections using different forms of insulin. Read on in chapter 13 for a lot more about insulin and insulin plans. Other people use insulin pumps to dispense insulin at a steady background, or basal, rate and to provide extra insulin to cover meals. More about insulin pumps can be found in chapter 13.

Although today’s insulin pumps are worn externally, researchers are developing and testing pumps that are placed inside the body. Ideally, the pump would sense the amount of glucose in the blood and deliver the right amount of insulin, as needed. These pumps are called closed-loop systems.

Your type of insulin therapy should relate directly to your health and your lifestyle choices. Your chosen therapy may aim to keep your blood glucose levels from shooting too high after meals or falling too low between meals. Or your therapy may aim to keep after-meal blood glucose levels as close as possible to those of someone without diabetes.

The food you eat and the exercise you get go hand in hand with your insulin therapy. Of course, healthy eating and regular exercise are a part of everyone’s healthy living plan. But for you, knowing how these two daily features move your blood glucose level up and down is essential.

To know how much insulin you’ll need to have, it helps to know:

• Your current blood glucose level (you know this by blood glucose testing).

• What you plan to eat (so you can estimate how much your blood glucose will increase).

• What physical activities you plan to do.

There is more information about insulin therapy and different insulin plans in chapter 13, and more about healthy eating in chapter 10. Read about physical activity and exercise for people with type 1 diabetes in chapter 11.

Pancreas Transplants

So far, the only way to treat type 1 diabetes is to give the body another source of insulin. Usually, this is done through insulin injections. However, new experimental approaches also show some promise.

Some patients with type 1 diabetes have experienced positive results from pancreas transplants. Typically, part or all of a new pancreas is surgically implanted. The old pancreas is left alone; it still makes digestive enzymes, even though it doesn’t make insulin. Most organs are obtained from someone who has died but decided to be an organ donor.

A transplant of the pancreas is usually reserved for those with serious complications. Pancreas transplants are most often done when a patient also receives a new kidney. The pancreas transplant adds little further risk and offers big benefits. However, transplant surgery is risky. Each person needs to carefully weigh the potential benefits and risks.

Benefits of Pancreas Transplants

• You may be able to maintain a normal blood glucose level without taking insulin.

• Many of the diabetes-related side effects are prevented or delayed.

• Most people with nerve damage who receive a pancreas transplant do not get worse and sometimes show improvement.


Downsides to Pancreas Transplants

• The body treats the new pancreas as foreign and the immune system attacks the transplanted pancreas.

• Transplant patients must take powerful immunosuppressant drugs to prevent rejection of the new pancreas. Drugs that suppress the immune system can lower resistance to other diseases, such as cancer, and to bacterial and viral infections.

Islet Transplants

Researchers are testing transplanting only the islet cells of the pancreas. These are the cells in the pancreas that secrete insulin. The islets also sense glucose levels in the blood and dispense the right amount of insulin to the blood.

Islets from a deceased person are taken out, purified, and then transferred to a person with type 1 diabetes. These cells then go on to make insulin.

The procedure has been beneficial for some people—allowing them to take less or sometimes no insulin. However, islet transplantation is still considered experimental.

Organ Donors

One of the biggest problems with both pancreas and islet cell transplantation is the shortage of organ donors. About 7,000 bodies are donated for organ transplants each year in the United States—too few to supply islet cells for everyone with type 1 diabetes.


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