Type 1 diabetes doesn’t develop overnight. Before a person is aware of having the condition, it may already be well under way in its progression. Most people don’t have any symptoms during the first two stages and are diagnosed in the third stage.

If you understand the three stages of type 1 diabetes, you may be able to delay the onset of the final stage and avoid potentially dangerous symptoms.

How Does Type 1 Diabetes Develop?

Type 1 diabetes is an autoimmune disease that causes glucose (blood sugar) to rise too high. With an autoimmune disease, your immune system — which usually protects your body from foreign invaders — mistakenly attacks and destroys healthy tissue.

Your blood sugar is normally regulated by a hormone called insulin, which is made by your pancreas. Insulin helps usher glucose out of blood and into cells throughout your body so it can be used to make energy. If you have type 1 diabetes, genetic and environmental factors can cause your immune system to start attacking insulin-producing cells in your pancreas called beta cells.

To fight invaders, your immune system makes specialized immune proteins called antibodies. When antibodies target your own body tissues, they’re known as autoantibodies. In type 1 diabetes, your immune system makes autoantibodies against insulin-producing cells. If your beta cells are destroyed, your body can’t make insulin. Without insulin, glucose rises in the blood and can’t be used by cells to make energy.

Type 1 diabetes doesn’t occur suddenly — researchers have identified three stages of development. The speed of progression from one stage to the next differs among individuals. However, the lifetime risk of symptomatic diabetes for people with any stage of type 1 diabetes is nearly 100 percent, according to a study in the journal Diabetes Care.

Continue reading to learn more about the three stages of type 1 diabetes.

Stage 1: Normal Blood Sugar Without Symptoms

In stage 1, your immune system has begun to make diabetes-related autoantibodies, but you don’t have any signs or symptoms of diabetes. People in stage 1 will have enough insulin for normal blood sugar readings but will test positive for diabetes-related autoantibodies.

About 44 percent of children with stage 1 type 1 diabetes begin to have symptoms within five years, according to Diabetes Care. In 10 years, 70 percent of children at stage 1 have diabetes symptoms. Research has found that nearly everyone at stage 1 eventually develops stage 3 type 1 diabetes.

Tests for Stage 1

Even when no symptoms are present, stage 1 type 1 diabetes can be detected with a screening test. These tests reveal signs of the disease before you experience any symptoms.

The screening tests check for the presence of diabetes-related autoantibodies. Your results are considered positive if you have two or more of these autoantibodies.

Not everyone gets screened for type 1 diabetes. You may qualify for a screening test if you have a family history of type 1 diabetes. For example, if you have a first-degree relative (parent, sibling, or child) who has been diagnosed with type 1 diabetes, you may be able to be screened.

If you have a family member with type 1 diabetes, you have about a 15 times higher risk of developing type 1 diabetes compared with the general population. Talk to your health care provider to find out if you qualify for screening tests. In the United States, screening tests may be available through your doctor’s office or through a research program like TrialNet.

Stage 2: Abnormal Blood Sugar Without Symptoms

In stage 2, you may start to have abnormal blood sugar levels but still not show any symptoms of diabetes. In this stage, beta-cell loss caused by your immune system can reduce insulin and lead to abnormal blood sugar levels. Even so, you may not yet have symptoms of type 1 diabetes.

About 75 percent of people with stage 2 type 1 diabetes progress to develop diabetes symptoms within five years, according to Diabetes Care.

Tests for Stage 2

If you have stage 2 type 1 diabetes, you’ll test positive for two or more diabetes-related autoantibodies. You might not have any symptoms, but tests for your blood sugar may start to be abnormal.

To help diagnose stage 2 type 1 diabetes, your doctor may order glucose tests such as:

• Random plasma glucose — Measures your blood sugar level at any point in time
• Fasting plasma glucose — Measures your blood sugar level when you haven’t had anything to eat or drink in eight to 12 hours
• Oral glucose tolerance test — Measures your body’s response to sugar
• A1c blood test — Checks your average blood sugar level over the past three months

Talk to your doctor about additional testing you may need if you have diabetes-related autoantibodies.

Stage 3: Clinical Diagnosis of Type 1 Diabetes

People with stage 3 type 1 diabetes have two or more diabetes-related autoantibodies, abnormal blood sugar, and symptoms of diabetes. This is when a diabetes diagnosis is made.

At this stage, you start to develop symptoms. In the past, doctors considered stage 3 type 1 diabetes to be the start of the disease. Research has revealed that this isn’t the beginning of the disease but, rather, the point at which a clinical diagnosis can be made.

Symptoms of type 1 diabetes include:

• Greater thirst
• Frequent urination
• Blurry vision
• Extreme tiredness
• Frequent hunger
• Unexplained weight loss

If type 1 diabetes is undetected, you may develop symptoms of a life-threatening condition called diabetic ketoacidosis (DKA). This condition can occur when blood sugar levels are very high and insulin levels are very low. With no available glucose, the body instead uses fats to make energy. This process causes production of some acids called ketones. Symptoms of DKA include:

• Nausea, vomiting, and stomach pain
• Confusion or trouble paying attention
• Fruity-smelling breath
• Dry mouth
• Dry or flushed skin
• Headache
• Muscle aches

Tests for Stage 3

Type 1 diabetes is usually diagnosed based on the signs and symptoms of diabetes. If you have diabetes symptoms but no diagnosis yet, your doctor can diagnose type 1 diabetes based on blood sugar tests and autoantibody tests. Just like at stages 1 and 2, people with stage 3 type 1 diabetes will have two or more diabetes-related autoantibodies.

How Is Each Stage Treated?

Stages 1 and 2 type 1 diabetes may be treated with frequent monitoring and follow-up with a doctor who specializes in diagnosing and treating diabetes, called an endocrinologist.

For stage 3 type 1 diabetes, the primary treatment is insulin replacement therapy. In some cases, insulin may be started in people who have stage 2 type 1 diabetes without symptoms. There are many types of insulin and several ways to take it, such as using an insulin pump. Talk to your doctor about the best type of insulin for you.

Early detection of type 1 diabetes can help you and your doctor develop a monitoring plan to avoid life-threatening complications, such as diabetic ketoacidosis.

Can You Prevent Stage 3 Type 1 Diabetes?

Currently, there’s no way to prevent diabetes type 1 from advancing through the three stages. However, if the condition is detected at an early stage, type 1 diabetes progression may be delayed. The drug teplizumab (Tzield) has been approved by the U.S. Food and Drug Administration (FDA) to delay the onset of stage 3 type 1 diabetes in adults and children older than 8 years. Teplizumab prevents your immune system from attacking beta cells. In clinical trials, it delayed the onset of diabetes by about three years.

If screening results show you have an early stage of type 1 diabetes, ask your health care provider if you qualify to take teplizumab or participate in a clinical trial to find new ways of slowing or stopping type 1 diabetes progression.

Talk to your doctor if you have any questions about the staging, testing, or treatment of type 1 diabetes in yourself or your children. Type 1 diabetes can be treated and managed, and your health care provider can help you find the best plan for living with diabetes.

Talk With Others Who Understand

On myT1Dteam — the social network for people living with type 1 diabetes and their loved ones — members come together to ask questions, give advice, and share their stories with those who understand life with type 1 diabetes.

Have you or a family member had diabetes screening tests? At which stage did you discover type 1 diabetes? Share your experiences in a comment below, or post to your Activities page.