Type 1 Diabetes


What is Type 1 diabetes?

Type 1 diabetes is a disease that prevents your pancreas from making insulin. In some cases, it doesn’t make any insulin. In other cases, it doesn’t make enough. Insulin is a hormone that regulates the amount of glucose (sugar) in your blood. It helps glucose from food get into your cells to use for energy.

If you don’t have enough insulin, too much sugar builds up in your blood. Hyperglycemia (high blood sugar) can lead to serious health problems or even death. People with Type 1 diabetes need insulin each day.

Type 1 diabetes was previously known as juvenile diabetes or insulin-dependent diabetes.

How are Type 1 diabetes and Type 2 diabetes different?

Type 1 diabetes is not the same as Type 2 diabetes. In Type 2 diabetes, your pancreas does make insulin, but your body doesn’t respond to it like it should. Both types are forms of diabetes mellitus, meaning they lead to too much sugar in your blood.

Who gets Type 1 diabetes?

Anyone can get Type 1 diabetes, though it’s more common in children and young adults. People with a family history of Type 1 diabetes may be more likely to develop the disease.

How common is Type 1 diabetes?

About 1.6 million Americans have Type 1 diabetes. Only about 5% of all people with diabetes have Type 1. Type 2 diabetes is much more common.

Symptoms and Causes

What causes Type 1 diabetes?

Type 1 diabetes develops when your immune system mistakenly attacks cells in your pancreas that make insulin. Viruses might trigger this immune reaction. Some people may also have an abnormal gene that decreases insulin production.

What are the symptoms of Type 1 diabetes?

Symptoms of Type 1 diabetes can include:

Some people with undiagnosed or untreated Type 1 diabetes develop diabetes-related ketoacidosis (DKA). This is a condition where your body processes fat instead of glucose for energy. Substances called ketones build up and make your blood acidic. DKA is a life-threatening condition that requires immediate medical attention.

Symptoms of DKA include:

What are the complications of Type 1 diabetes?

Potential complications of Type 1 diabetes are the same as potential complications of Type 2 diabetes and can include:

Diagnosis and Tests

How is Type 1 diabetes diagnosed?

The following blood tests help your healthcare provider diagnose diabetes:

  • Blood glucose test: Your healthcare provider uses a blood glucose test to check the amount of sugar in your blood. They may ask you to do a random test (without fasting) and a fasting test (no food or drink for at least eight hours before the test).
  • Glycolated hemoglobin test (A1c): If blood glucose test results indicate that you have diabetes, your healthcare provider may do an A1c test. This measures your average blood sugar levels over three months.
  • Antibody test: A blood test checks for autoantibodies to determine if you have Type 1 or Type 2 diabetes. Autoantibodies are proteins that attack your body’s own tissue by mistake. The presence of certain autoantibodies means you have Type 1 diabetes. Autoantibodies usually aren’t present in Type 2 diabetes.

Management and Treatment

How is Type 1 diabetes treated?

People with Type 1 diabetes need to replenish their insulin each day. There are different types of insulin. Some insulin starts acting as soon as you take the medicine; other insulins take several hours to work. The various types of insulin also last in your body for different lengths of time. Some are more expensive than others. Work with your doctor to find the right type of insulin for your needs.

How do I take insulin?

You can take insulin in one of the following ways:

  • Injection: Injectable insulin uses a vial and syringe. With each injection, you use a syringe to get the correct dose of insulin out of the vial. Insulin can be injected into the fatty tissue of your belly, upper arm, thigh or buttocks. Injections are usually the least expensive way to take insulin.
  • Pen: Insulin pens are similar to injections, but the pen is pre-filled with insulin. The disposable pen needles are usually more convenient than shots. They can also be a good option for people with low vision.
  • Pump: Insulin pumps are devices that deliver insulin continuously and on demand. They mimic the way your pancreas would naturally release insulin. Pumps deliver insulin through a tiny catheter (thin, flexible tube) that goes in your belly or another fleshy area of your body.

Your healthcare provider may recommend three to four doses of insulin each day. Long-acting insulin usually works best when taken at about the same time every day. Take rapid-acting insulin within 15 minutes before a meal. This ensures it’s ready to work when glucose from food enters your blood.

Are there other ways to manage Type 1 diabetes?

People with Type 1 diabetes need to monitor their blood sugar closely. Maintaining a healthy blood sugar range is the best way to avoid health complications. You can monitor your blood sugar in the following ways:

  • Blood glucose meter: You prick your finger and put a small drop of blood on the meter’s test strip. Your blood glucose level appears on the meter. A blood glucose meter is usually the least expensive home testing option, but it only reports your blood sugar at the time of the check.
  • Continuous glucose monitoring (CGM): There are different types of CGMs. Most CGMs require you to insert a small sensor under your skin at home every seven to 14 days. Some CGMs are implanted by a healthcare provider. The sensor continuously records your blood glucose levels. People using a CGM require fewer finger sticks. CGM systems can be more expensive than fingerstick blood glucose meters, but they provide much more information about your glucose levels, including where they have been and where they are going.

What is my target blood glucose level?

Your healthcare provider will tell you what your target blood glucose level should be. It depends on a variety of factors, including your:

  • Age.
  • Health.
  • How long you’ve had diabetes.

How does my diet affect diabetes?

A healthy diet is an important part of managing Type 1 diabetes. The right foods can help keep your blood pressure and blood glucose in check. Healthy meal planning for people without Type 1 diabetes is similar to healthy meal planning for people with Type 1 diabetes:

  • Avoid foods with added sugar, sodium (salt) and trans fats.
  • Eat a balance of proteins, carbohydrates and healthy fats.
  • Read nutrition labels to select foods with more fiber and less sugar.
  • Skip the highly processed foods found in cans or packages.

In addition, it's important for people with Type 1 diabetes to understand how foods with carbohydrates (carbs) impact their blood sugar levels and how much insulin to take for various amounts of carbs. Work with your healthcare team to figure out the best plan for you.


How can I prevent Type 1 diabetes?

There’s no way to prevent Type 1 diabetes. But you can help prevent complications by:

  • Maintaining target blood glucose levels.
  • Monitoring your blood glucose closely.
  • Taking care of your health through healthy eating and activity.
  • Learning how to manage stress and illness.

Outlook / Prognosis

What is the outlook for Type 1 diabetes?

By keeping blood sugar levels mostly in the target ranges, people with Type 1 diabetes can live happy and healthy lives. Work with your healthcare provider to build the most effective diabetes management plan for your needs.

Living With

When should I call my doctor?

Contact your healthcare provider if you experience any symptoms of Type 1 diabetes. Don’t ignore the signs. Untreated diabetes can lead to serious health problems, including coma or death.

Seek immediate medical attention if you develop symptoms of diabetes-related ketoacidosis (DKA).

How should I manage sick days?

People with diabetes need to monitor their health especially carefully if they get sick. Illnesses as common as a cold or the flu can be dangerous if they interfere with your food intake, insulin delivery, and blood sugar levels. Make a “sick day” plan with your healthcare provider so you know how often to check your blood sugar and what medications to take.

A note from Cleveland Clinic

Type 1 diabetes is a disease that prevents your pancreas from making enough insulin. It causes glucose (sugar) to build up in your blood. High blood glucose levels can lead to serious health problems, including nerve damage, heart disease or stroke. People with Type 1 diabetes need to monitor their blood glucose levels closely and take insulin regularly.

Last reviewed by a Cleveland Clinic medical professional on 07/07/2021.


  • American Diabetes Association. Statistics About Diabetes. (https://www.diabetes.org/resources/statistics/statistics-about-diabetes) Accessed 7/8/2021.
  • American Diabetes Association. Medication & Treatments. (https://www.diabetes.org/healthy-living/medication-treatments) Accessed 7/8/2021.
  • Centers for Disease Control and Prevention. Diabetes Basics. (https://www.cdc.gov/diabetes/basics/index.html) Accessed 7/8/2021.
  • National Institute of Diabetes and Digestive and Kidney Diseases. Type 1 Diabetes. (https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/type-1-diabetes) Accessed 7/8/2021.

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