Type 1 Diabetes

January 7, 2025

This page was reviewed under our medical and editorial policy by Ping H. Wang, M.D., professor and chair, Department of Diabetes, Endocrinology & Metabolism, City of Hope^® Cancer Center Duarte

Type 1 diabetes is the second most common type of diabetes overall, and the most common type in children and young adults under the age of 20. The condition typically first develops in children, but it may also develop in adults at any age.

About 1.7 million adults have type 1 diabetes, according to the U.S. Centers for Disease Control and Prevention, and approximately 304,000 children and adolescents are living with type 1 diabetes.

What Is Type 1 Diabetes?

Type 1 diabetes is considered an autoimmune disease. This means that the body’s immune system mistakes tissues or cells in the body as foreign invaders and attacks them, making it hard for the cells or organ to function.

In type 1 diabetes, the immune system attacks and destroys the beta cells in the pancreas that make insulin. Insulin is a hormone that works to move glucose (sugar) from the bloodstream into the cells. Cells require this sugar for energy in order to survive, but in type 1 diabetes, little to no insulin is produced by the pancreas, so the sugar builds up in the bloodstream. This is why everyone diagnosed with type 1 diabetes must take insulin injections and monitor their blood glucose (sugar) levels closely.

Type 1 Versus Type 2 Diabetes

In type 1 diabetes, the immune system sees the beta cells that make insulin as foreign invaders and works to destroy them. This means little to no insulin is being made. Children and adults who are diagnosed with type 1 diabetes must take insulin each day to keep their blood sugar levels in check.

In type 2 diabetes, insulin is produced, but the cells in fatty tissue, muscles and liver become less sensitive to the hormone. This means insulin does not work well at moving sugar (glucose) from the bloodstream into these cells for energy. This is known as insulin resistance. People with type 2 diabetes may need to take oral medications, and sometimes insulin injections, to help balance their blood sugar. Lifestyle practices like eating a healthy diet for diabetes and exercising are also used to help manage the condition.

In the majority of cases, type 1 diabetes develops in children or adolescents, while type 2 diabetes mainly develops in middle-aged or older adults. However, both types may develop at any age.

Type 1 Diabetes Symptoms

For some people, symptoms of type 1 diabetes develop suddenly and quickly in weeks or months. For others, the harm to the pancreas and symptoms may happen more gradually, over years. Symptoms may include:

• Excessive urination, especially during the night
• Excessive thirst
• Unexplained weight loss
• Fatigue
• Dry mouth and dry skin
• An abnormal number of infections
• Slow-healing wounds
• Blurry vision
• Nausea
• Vomiting
• Breath that has a fruit-like odor
• Headaches
• Stomach pain
• Tingling, numbness or pain in the hands or feet
• Flushed face
• Rapid breathing

People who experience nausea, vomiting, stomach pain, fruity breath, rapid breathing, dry skin or mouth, and a flushed face may have a life-threatening diabetes complication called diabetic ketoacidosis (DKA).

In DKA, the body breaks down fat into ketones (fuel) too quickly. While these ketones are meant to be an alternate energy source for cells when glucose is not reaching them, they may build up in the bloodstream too fast and cause toxicity. That is why it is important to seek emergency medical attention right away if these symptoms occur.

Signs of Type 1 Diabetes in Kids

Parents may notice certain changes in their child over days or months. Common symptoms of type 1 diabetes in children may include:

• Becoming thinner
• Constant thirst, no matter how much they drink (polydipsia)
• Extreme hunger
• Urinating a lot more than usual (polyuria), and bedwetting, even if they have already been potty-trained
• Flu-like symptoms, such as vomiting, dehydration, loss of appetite and/or low energy (either physically, mentally or both)
• More infections than usual, such as yeast infections in girls
• Blurred vision
• Irritability or moodiness
• Diaper rash, in small children, that may be severe (although it responds well to treatment).
• DKA, which affects a significant portion of children who are diagnosed with type 1 diabetes

If a child has DKA, his or her parents may notice a flushed appearance, fruity breath, vomiting or rapid, deep breathing. The child may also complain of nausea and stomach pain. It is important to call emergency services right away if these symptoms persist because DKA needs to be treated as quickly as possible.

Late Onset Type 1 Diabetes Symptoms

Sometimes type 1 diabetes develops more slowly over time, which means a person’s beta cells (insulin makers) are not destroyed as quickly. This is known as late onset type 1 diabetes or latent autoimmune diabetes in adults (LADA).

LADA does not always cause noticeable symptoms. LADA has some symptoms in common with type 2 diabetes, such as insulin resistance, and some in common with type 1 diabetes. Patients with LADA may notice:

• Fatigue
• Weight loss
• Needing to urinate often
• Very thirsty
• Waking up at night to urinate
• Visual changes
• Tingling in the feet

Doctors may diagnose LADA if a patient:

• Is over age 30
• Does not need to rely on insulin right away (for at least six months after their diagnosis)
• Has proteins in their immune system called autoantibodies that attack the beta cells

LADA may initially be treated or managed using lifestyle changes like exercise and a healthy diet. Medication is also given to help keep beta cells functioning. Patients will need to take insulin once the condition progresses to a stage where beta cells become too depleted.

What Causes Type 1 Diabetes?

The exact causes of type 1 diabetes are still being researched.

Scientists have found evidence that a combination of genes and environmental factors may cause the body’s own immune system to fight and destroy beta cells made in the pancreas. This immune system attack on the body’s own cells is known as an autoimmune reaction. A number of gene changes (variants) have been identified that may make a person more at risk for developing this autoimmune reaction when environmental factors (like viral infections) come into play. Certain variants in the HLA gene have been tied to a higher risk of type 1 diabetes. These gene variants are sometimes passed down through family members.

Risk Factors

Type 1 diabetes risk factors may include:

• A family history of the disease, especially if a parent or sibling is diagnosed with it
• Certain genes, particularly human leukocyte antigen (HLA) class 2 genes
• Infections, especially if they occur before birth and in infancy and early childhood

Children and young adults are more likely to develop type 1 diabetes than older adults. In the United States, white people are at higher risk for the condition than Hispanic, African American or Latino people.

Is Type 1 Diabetes Genetic?

Yes, type 1 diabetes may be genetic, but it is a complex process. Genetic factors contribute to roughly half of the type 1 diabetes risk, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

Certain HLA genes that create instructions for proteins critical to immune system operations have been identified as key contributors to the disease. However, only about 5% of people with these gene variants go on to develop type 1 diabetes, according to MedlinePlus. Additional genes and environmental factors also play a role in type 1 diabetes development.

The Diagnosis Process

Doctors use different tests to accurately diagnose type 1 diabetes.

Random plasma glucose (RPG) test: This blood test is used to determine blood glucose (sugar) levels for people with diabetes symptoms who prefer not to fast for eight hours. It tests blood sugar levels at the moment. Blood glucose levels of 200 milligrams per deciliter (mg/dL) may indicate that a person has diabetes.

A1C test: Rather than a one-time measurement of blood sugar levels, this blood test measures a person’s average blood sugar levels over the previous three months. It does this by measuring how much blood sugar is attached to a protein called hemoglobin. Sugar binds with hemoglobin when entering the bloodstream, and hemoglobin only regenerates roughly every three months. A reading of 6.5% or higher indicates diabetes.

Fasting glucose test: In this test, the doctor will have the patient fast overnight or for at least eight hours — meaning they should not eat or drink during this time, except for sips of water. Fasting blood glucose levels of 126 mg/dL or higher may indicate that a person has diabetes.

Oral glucose tolerance test: This is a two-hour test that checks blood glucose levels before and then two hours after patients consume a special sweet drink. At two hours, if blood glucose is at or above 200 mg/dL, diabetes is diagnosed.

Doctors may also perform other tests to help make the diagnosis. For example, after a patient is diagnosed with diabetes, the care team may perform autoantibody blood tests. These tests look for proteins in the person’s immune system called autoantibodies that attack the beta cells that produce insulin. These autoantibodies are present in type 1 diabetes and a small percentage of type 2 diabetes patients. Not everyone with autoantibodies develops diabetes.

The doctor may also check for ketones in the person’s urine, which indicates a lack of insulin production. This may help indicate whether the patient has a serious diabetes complication called diabetic ketoacidosis.

Type 1 Diabetes Treatment

The first step in treating type 1 diabetes is to get the patient’s blood sugar levels under control. The standard approach is to start patients on insulin therapy. The diabetic care team typically includes doctors, clinical pharmacists, dietitians and certified diabetes care and education specialists (CDCES).

Patients with type 1 diabetes take insulin to help control blood sugar for the rest of their lives, typically every day. Different ways of injecting are available for patients to try out, such as injections or infusion through insulin pumps.

Additional diabetes treatment medications may be prescribed by the doctor as well, such as SymlinPen^® (pramlintide) to help regulate blood sugar levels right after mealtimes. All patients must start a blood sugar monitoring regimen, such as using a continuous glucose monitoring (CGM) device.

Diabetes management strategies may also include:

• Following a diabetic meal plan recommended by the care team
• Exercising regularly
• Checking blood sugar levels daily using tools like a continuous glucose monitor or a glucose meter and testing strips
• Improved foot care strategies, such as monitoring feet regularly for signs of wounds or an infection
• Implementing prevention strategies for cardiovascular diseases
• Preventing other diabetes complications

Those diagnosed with diabetes are also encouraged to stop using tobacco products, monitor their blood pressure and talk with their doctor about scheduling regular cholesterol checkups.

Parents with younger children will need to give them insulin every day, help them monitor their blood glucose levels and guide their child and other caregivers through the insulin schedule and diabetic management strategies.

Can Type 1 Diabetes Be Cured?

There is currently no cure for type 1 diabetes. However, scientists are actively exploring new strategies toward a potential cure. While type 1 diabetes is a lifelong condition, with proper management, people diagnosed with the condition often live active, healthy lives.

Patients and their loved ones are encouraged to learn proper treatment and management strategies from their care team, such as glucose testing and eating a healthy diet that supports proper blood sugar levels.

Type 1 Diabetes Complications

The high blood sugar that is a hallmark of type 1 diabetes may lead to a variety of health issues and complications, especially if it is left untreated. These health issues may include:

• Heart disease
• Stroke
• Kidney disease
• Gum disease
• Vision loss
• Depression
• Foot problems like numbness, pain and wounds that won’t heal
• Diabetic neuropathy (nerve damage)
• Skin infections
• Sexual issues like erectile dysfunction in men and low desire in women
• Bladder issues like urinary incontinence (involuntary urination)
• Sleep apnea

Diabetes also increases the risk of developing some types of cancer and dementia.

Type 1 Diabetes Life Expectancy

Life expectancy has been improving for people diagnosed with type 1 diabetes. One study in the journal Diabetes found that the life expectancy of people diagnosed with the condition between 1950 and 1964 was 53.4 years, while it was 68.8 years for those diagnosed between 1965 and 1980.

Survival rates have improved significantly over the past several decades and may continue improving in the future. A 2022 study found that diabetes survival also depends on age of onset, socioeconomic status and other factors. Patients should talk to their endocrinology team about their prognosis based on the specifics of their type 1 diabetes diagnosis.