Type 1 Diabetes

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is type 1 diabetes?

Type 1 diabetes is one of two main types of diabetes—a group of disorders that all have the hallmark sign of high blood sugar, or hyperglycemia. Type 1 diabetes most often develops in children but can occur at any age. The National Institutes of Health (NIH) estimates that 5 to 10% of diabetes cases in adults are type 1.

About 1.6 million people (1.4 million adults aged 20 or older, plus 200,000 children) in the United States have type 1 diabetes, according to the U.S. Centers for Disease Control and Prevention. The organization also estimates about 20,000 people younger than 20 are newly diagnosed every year. The incidence of type 1 diabetes has been increasing.

Type 1 diabetes used to be called juvenile diabetes or insulin-dependent diabetes. This reflected the fact that it is common to diagnose it in the childhood years and requires insulin treatment. However, those names aren’t entirely accurate because adults can get type 1 diabetes and people with type 2 diabetes can depend on insulin as well. Today, doctors recognize the two main types of diabetes—type 1 vs. type 2 diabetes—by how they develop.

Type 1 diabetes is the result of beta cell destruction in the pancreas. Beta cells make insulin, the hormone your cells need to turn sugar from food into energy. Without insulin, your body can’t use sugar for fuel. Instead, the sugar remains in the bloodstream causing high blood sugar, or hyperglycemia. Type 2 diabetes stems from a problem with normal insulin signaling that ultimately leads to insulin resistance.

The three main symptoms of hyperglycemia are excessive hunger, thirst and urination. They tend to develop suddenly. Seek prompt medical attention if you have these symptoms or notice them in your child.

What are the symptoms of type 1 diabetes?

In type 1 diabetes, beta cell destruction can happen over months or years. However, once enough beta cells no longer function, symptoms can start quickly. They can become noticeable in a few weeks and tend to be severe.

Common symptoms of type 1 diabetes

The most common type 1 diabetes symptoms include:

  • Blurred vision
  • Dramatically increased hunger, which may lead to irritability
  • Excessive thirst and urination, which can include bed wetting in children who had been dry at night
  • Mood changes

Childhood symptoms of type 1 diabetes

When thinking about a young child with symptoms of diabetes, consider how they might communicate their symptoms. Do they:

  • Go to the bathroom all day long?
  • Ask for something to drink more often than usual?
  • Tell you that they are always hungry or can’t seem to eat enough?
  • Tell you that they are too tired to go to school or even play with their friends?
  • Complain about prickling, or a pins-and-needles feeling in their hands or feet?
  • Complain about not feeling well even though they don’t have obvious symptoms?

Serious symptoms that might indicate a life-threatening condition

Sometimes, type 1 diabetes causes blood sugar to go so high that it becomes life-threatening. This condition is ketoacidosis. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Fruity or sweet-smelling breath

Regular medical care throughout life can help identify early signs and symptoms of type 1 diabetes. Because symptoms often develop suddenly, it’s important to see your doctor when you first notice them. Your doctor can determine whether diabetes or some other condition is at the root of the problem.

What causes type 1 diabetes?

Doctors and researchers do not know for sure what exactly causes type 1 diabetes. It is most likely an autoimmune disease, meaning your immune system attacks your own cells as if they were foreign substances. In type 1 diabetes, your immune system targets and attacks the insulin-producing beta cells in the pancreas. When glucose cannot enter the cells, it builds up in the blood, depriving the cells of an immediate source of energy. In the meantime the body’s metabolism utilizes alternate pathways to manage the chronically elevated blood glucose levels, a process that yields toxic complications over time.

Why the immune system targets and attacks beta cells is less well understood. Most experts believe it is a combination of genetic and environmental factors. Some people may have genes that increase their risk of developing type 1 diabetes. It is also possible that some sort of trigger, such as a viral infection, ignites the autoimmune process.

What are the risk factors for type 1 diabetes?

Currently, there is limited information about risk factors for type 1 diabetes. However, there are a few factors doctors know about that increase the risk of developing type 1 diabetes.

These risk factors include:

  • Age: You can get type 1 diabetes at any age, but it commonly develops during childhood, teenage years, and early adulthood.
  • Family history: People who have a parent or sibling with type 1 diabetes are more likely to develop the disease. This may be due to certain genes passing down in a family.
  • Geography: Type 1 diabetes tends to occur more frequently in northern climates, as you get farther away from the equator.
  • Race: In the United States, Caucasians tend to develop type 1 diabetes more often than other races.

Reducing your risk of type 1 diabetes

There is no known way to prevent or reduce your risk of type 1 diabetes. This reinforces the importance of seeing your doctor on a regular basis if you are at risk for the disease. If you need more information about your risk, talk with your doctor.

What are some conditions related to type 1 diabetes?

Type 1 diabetes is related to type 2 diabetes in terms of blood sugar control, but not in terms of the underlying cause. Type 1 diabetes may be associated with other autoimmune diseases. Diseases that are more common in people with type 1 diabetes include:

  • Addison’s disease, a disorder affecting the adrenal glands
  • Celiac disease, an autoimmune disease that damages the lining of the small intestine

How do doctors diagnose type 1 diabetes?

If a patient has signs and symptoms of diabetes, blood and urine tests can help the doctor determine if it is type 1 or type 2 diabetes.

Type 1 diabetes tests include:

  • Antibody tests. Specific types of blood tests can reveal whether you have autoimmune antibodies common in people with type 1 diabetes: islet cell autoantibodies (ICA), glutamic acid decarboxylase autoantibodies (GAD-65), insulin autoantibodies(IAA), and protein tyrosine phosphatase autoantibodies (IA-2A).
  • Fasting blood sugar test. A level of 126 mg/dL or higher indicates diabetes.
  • Glycated hemoglobin (HbA1C) test. HbA1C is a test that represents how well your body controlled blood sugar over the last 2 to 3 months. Higher levels of sugar-modified hemoglobin mean higher blood sugar levels. You likely have diabetes if the value is 6.5% or higher at two different testing dates.
  • Random blood sugar test. A level of 200 mg/dL (milligrams per deciliter) or higher indicates diabetes.
  • Urine ketone test. If you have type 1 diabetes, your body cannot use sugar from food for energy, so it breaks down fat as a source of energy. Ketones are a breakdown product of fat.

How is type 1 diabetes treated?

The goal of type 1 diabetes treatment is to normalize blood sugar levels. For most people, this means keeping blood sugar between 80 and 130 mg/dL. There are other targets, including after-meal blood sugar levels and HbA1C levels. HbA1C is a test that shows long-term blood sugar control over the last 2 to 3 months. In most cases, the goal result is 7%. Your doctor may have different target levels for you, depending on your specific situation.

Types of insulin

To accomplish these goals, people with type 1 diabetes need to use insulin because the body does not make any. There are different types of insulin based on how quickly and how long they work:

  • Rapid-acting insulin
  • Short-acting insulin
  • Intermediate-acting insulin
  • Long-acting insulin

Rapid- and short-acting insulins work to cover rises in blood sugar after meals. Intermediate- and long-acting insulins have a more gradual action to provide a basal level of insulin throughout the day.

How to take insulin and monitor blood sugar

The main ways to take insulin is by giving yourself injections throughout the day or using an insulin pump. People who use insulin injections use a needle and syringe to inject insulin under the skin. An insulin pump is a small device on the outside of your body that delivers insulin under your skin through a small catheter.

When you use insulin, you need to monitor your blood sugar throughout the day. These measurements help you fine-tune your insulin dose. It can also tell you if your blood sugar levels are getting too high or too low.

There are two main ways to check your blood glucose—a glucometer or a continuous glucose monitor (CGM). With a glucometer, you prick your finger several times a day to check your blood sugar. A CGM has a sensor under your skin that checks your blood sugar every few minutes. Many people with type 1 diabetes use a CGM because it is especially helpful for preventing hypoglycemia—low blood sugar. It also shows you the rate and direction of your blood sugar levels.

Artificial pancreas

CGM technology paired with an insulin pump is known as a hybrid closed-loop system, or artificial pancreas. The system monitors blood sugar and delivers basal insulin as necessary. However, it requires information from you about meals in order to deliver short-acting insulin doses. Someday, a fully closed-loop system may be available.

Other components of type 1 diabetes treatment

Type 1 diabetes treatment also includes:

  • Carbohydrate counting and monitoring
  • Food planning including meals, snacks and desserts
  • Regular exercise and physical activity

What are the diet and nutrition tips for type 1 diabetes?

Eating the right foods can help you manage type 1 diabetes because different foods affect blood sugar in different ways. The best foods to include in your diet are those high in nutrition and not likely to spike your blood glucose. Ask your healthcare provider for guidance before making significant changes to your diet.

Foods to include in a type 1 diabetes diet include:

  • Beans and nuts, which provide protein, fiber and nutrients without added sugar
  • Berries, which are a common “superfood” full of antioxidants, and citrus fruits
  • Fish high in omega-3 fatty acids
  • Poultry, which is another low-fat protein source
  • Whole grains without added sugar, which provide fiber and nutrients
  • Vegetables packed with nutrients and fiber, including non-iceberg lettuce (iceberg is lower in nutrients than other varieties), sweet potatoes, squash, and other vibrant vegetables

If you or a family member has type 1 diabetes, working with a diabetes dietitian may be helpful. This healthcare professional can provide diet and nutrition tips that will hold true for years to come.

How does type 1 diabetes affect quality of life?

Quality of life involves social and emotional, professional, and physical well-being. Studies investigating the quality of life of people living with type 1 vary considerably. Some show a broad and negative impact on quality of life, while others show no differences in quality of life between type 1 diabetics and a control population.

A 2020 study out of France looking at the quality of life of people living with type 1 diabetes for more than 40 years (diagnosed in 1970 to 1972) showed a high percentage were living a “fully rewarding life,” despite 97% of them monitoring blood sugar three times a day.

The effects of a chronic disease include its financial burden. Over a lifetime, people with type 1 diabetes spend about $75,000 more out-of-pocket on medical expenses than people without it, as determined by a simulation model of type 1 diabetes populations in the United States.

Your healthcare team can help you live well with type 1 diabetes by setting realistic blood glucose goals and supporting you along the way. The key to staying healthy with type 1 diabetes is learning how to take care of yourself.

Follow these tips for living with type 1 diabetes:

  • Know what to do if your blood sugar dips too low (hypoglycemia)
  • Celebrate your good blood glucose control
  • Embrace the support of family and friends, and/or find and join a support group
  • Check your feet daily
  • Touch base with your doctor regularly, and go to scheduled appointments
  • Stay up to date on type 1 diabetes research and treatment

What are the potential complications of type 1 diabetes?

There are several potential complications of type 1 diabetes and its treatment. One of the most common is hypoglycemia, which is when your blood sugar drops below your target range. There are three basic causes of hypoglycemia in type 1 diabetes:

  • Increased physical activity
  • Not enough food or carbohydrates
  • Too much insulin

Hypoglycemia warning signs include:

  • Hunger or nausea
  • Trembling, shakiness, anxiety, nervousness or irritability

If you have these symptoms, check your blood sugar. If your level is low, you need a quick source of sugar, such as glucose tablets. Other options include sugar, honey or fruit juice. Without adequate treatment, hypoglycemia can be life threatening. Seek immediate medical care (call 911) if someone with diabetes has low blood sugar symptoms that aren’t responding to treatment or if they have fainted or lost consciousness.

Other complications can develop if blood sugar levels remain uncontrolled above your target range. Chronically high blood sugar (hyperglycemia) damages nerves, blood vessels, and other tissues. This can result in heart disease, stroke, kidney damage, neuropathy, and eye, foot and skin problems. In women, it can cause pregnancy complications.

The best way to protect yourself and prevent diabetes complications is to follow your treatment plan closely.

Does type 1 diabetes shorten life expectancy?

Life expectancy is highly variable with or without diabetes. On average, type 1 diabetes prognosis is good and it is possible to have a normal life expectancy. But, coexisting medical conditions and other factors can have negative and positive impacts on one’s prognosis.

A Scottish study from 2015 showed an estimated reduction in life expectancy of 11 years for men and 13 years for women. Heart disease had the greatest effect overall, but before age 50, the greatest loss was due to diabetic coma or ketoacidosis. In another study, a simulation model showed that type 1 diabetes shortened life expectancy by nine years.

Over time, life expectancy of people with type 1 diabetes has been improving by years due to earlier diagnosis and improved diabetes care.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Apr 12
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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