Type 1 Diabetes Mellitus

Type 1 diabetes is a lifelong condition where your body cannot produce insulin, a vital hormone that controls blood sugar levels. While it often begins in childhood, it can develop at any age and requires daily management with insulin therapy.

Table of contents

• What is Type 1 Diabetes?
• Causes and Risk Factors
• Symptoms and Warning Signs
• Diagnosis
• Treatment and Management
• Possible Complications
• Living with Type 1 Diabetes

What is Type 1 Diabetes?

Type 1 diabetes is a chronic condition in which your body’s immune system mistakenly attacks and destroys the cells in your pancreas (an organ behind your stomach) that make insulin, a hormone your body needs to survive^[1][2]. Insulin acts like a key that allows sugar from your blood to enter your cells, where it can be used for energy. Without insulin, sugar builds up in your bloodstream instead of getting into your cells^[2].

This condition is called an autoimmune disease because your immune system, which normally protects you from infections, attacks healthy parts of your own body^[3]. When enough of these insulin-producing cells are destroyed, your pancreas can make little or no insulin, and you need to take insulin to live^[2].

Type 1 diabetes was previously known as juvenile diabetes or insulin-dependent diabetes^[3][4]. While it most commonly develops in children, teenagers, and young adults, it can happen at any age^[3][6]. In fact, there are more adults living with type 1 diabetes than children^[6]. In the United States, approximately 1.7 million adults have type 1 diabetes^[8].

Type 1 diabetes is different from type 2 diabetes, which is more common. Type 2 diabetes occurs when your body doesn’t make enough insulin or doesn’t use it properly, and it’s more often seen in older adults and people who are overweight^[9][10]. About 5 to 10 percent of all people with diabetes have type 1^[3][8].

Causes and Risk Factors

Scientists do not know the exact cause of type 1 diabetes, but they believe it happens when your immune system mistakenly attacks the insulin-producing cells in your pancreas^[1][3]. This destruction can go on for months or even years before any symptoms appear^[3][5].

Research shows that genetics likely play an important role. If you have a parent or sibling with type 1 diabetes, your chances of developing it are higher^[3][4]. Your risk of developing type 1 diabetes varies based on family connections: it’s about 1 in 250 if you have no family history, between 1 in 25 and 1 in 100 if your mother has it, 1 in 17 if your father has it, and between 1 in 10 and 1 in 4 if both parents have it^[4].

However, having the genes that increase risk doesn’t mean you will definitely develop type 1 diabetes. Many people with these genes never get the disease^[3]. Something in the environment, such as a virus or other triggers, may also play a part in starting the immune system’s attack if you have a genetic tendency toward the disease^[3][4].

Other known risk factors include age, as type 1 diabetes usually develops in children, teens, or young adults, though it can occur at any age^[3]. In the United States, white people are more likely to develop type 1 diabetes than African American and Hispanic or Latino people^[3].

Symptoms and Warning Signs

Type 1 diabetes symptoms can develop quickly, sometimes in just a few weeks or months^[3][4]. In some cases, symptoms may start mild and gradually become more severe over time^[4]. Common symptoms include:

• Excessive thirst
• Urinating frequently, including bedwetting in children who were previously dry at night
• Extreme hunger
• Unexplained weight loss
• Fatigue and weakness
• Blurred vision
• Slow healing of cuts and sores

These symptoms occur because without insulin, sugar cannot enter your cells for energy. Instead, it builds up in your bloodstream, causing hyperglycemia (high blood sugar)^[2][4]. Your body then tries to remove the excess sugar through urine, which leads to frequent urination and increased thirst.

If you or your child experience these symptoms, it’s important to see a healthcare provider right away and ask to be tested for type 1 diabetes^[3][4]. Some symptoms may be similar to other health conditions, so proper testing is essential.

Emergency warning signs: If type 1 diabetes goes undiagnosed and untreated, it can lead to a life-threatening condition called diabetic ketoacidosis (DKA)^[4]. This is more common in young patients with new-onset type 1 diabetes^[5]. Emergency signs include:

• Fruity-smelling breath
• Nausea and vomiting
• Abdominal pain
• Rapid breathing
• Confusion and extreme tiredness

Go to the emergency room immediately if you experience these symptoms, as DKA requires urgent medical treatment^[4].

Diagnosis

To diagnose type 1 diabetes, your healthcare provider will use blood tests to check your blood sugar levels^[11]. Common diagnostic tests include:

Glycated hemoglobin (A1C) test: This blood test shows your average blood sugar level for the past 2 to 3 months. An A1C level of 6.5 percent or higher on two separate tests indicates diabetes^[11].

Random blood sugar test: A blood sample taken at any time. A random blood sugar level of 200 mg/dL (11.1 mmol/L) or higher suggests diabetes, regardless of when you last ate^[11].

Fasting blood sugar test: A blood sample taken after you haven’t eaten overnight. A fasting blood sugar level of 126 mg/dL (7 mmol/L) or higher on two separate tests indicates diabetes^[11].

If you’re diagnosed with diabetes, your provider may run additional blood tests to check for autoantibodies (proteins your immune system makes when it attacks your own body) that are common in type 1 diabetes^[11]. These tests help your provider distinguish between type 1 and type 2 diabetes when the diagnosis isn’t certain. The presence of ketones (byproducts from the breakdown of fat) in your urine also suggests type 1 diabetes rather than type 2^[11].

Testing for type 1 diabetes, coupled with education about diabetes symptoms and close follow-up, has been shown to enable earlier diagnosis and prevent diabetic ketoacidosis^[2].

Treatment and Management

There is currently no cure for type 1 diabetes, but it can be managed successfully^[3][9]. The main treatment is lifelong insulin therapy combined with blood sugar monitoring, healthy eating, and regular physical activity^[3][5].

Insulin Therapy

Because your body cannot produce insulin, you must take it every day to survive^[2][3]. Insulin is given by injection or through an insulin pump (a small device you wear that delivers insulin continuously)^[14][19]. It doesn’t usually hurt because the needles are very small^[22].

Most people with type 1 diabetes use two types of insulin: basal insulin (long-acting insulin that works throughout the day) and bolus insulin (short-acting insulin taken with meals)^[14][16]. You’ll need to adjust your insulin dose based on what you eat and drink, your blood sugar levels, and how much you exercise^[22].

Some people use an insulin pump, which can reduce the risk of dangerously low blood sugar and improve blood sugar control compared to injections^[19]. More advanced systems called hybrid closed-loop systems combine an insulin pump with a continuous glucose monitor to automatically adjust insulin delivery based on your blood sugar levels^[17][19].

Blood Sugar Monitoring

Checking your blood sugar regularly is essential for managing type 1 diabetes^[22]. You can check it by pricking your finger with a small needle and using a blood glucose meter, or by using a continuous glucose monitor (CGM), which gives you readings at any time and reduces the number of finger-prick tests you need^[19][22].

It’s recommended that you check your blood sugar at least 4 times a day (or at least 5 times for children), including before meals and before bed^[22]. Check it more often when doing things that affect blood sugar, such as exercising or drinking alcohol, or when you’re sick^[22].

Healthy Eating and Carbohydrate Counting

Learning about nutrition is an important part of managing type 1 diabetes^[27]. Knowing how many carbohydrates (carbs) you’re eating helps you match your insulin dose to your food, giving you more flexibility in what you eat^[22].

Rather than eating three large meals a day, eating smaller meals throughout the day can help keep your blood sugar from spiking and dropping dramatically^[26]. Focus on whole foods that aren’t overly processed, and learn to read food labels to find hidden sugar^[26].

Physical Activity

Regular exercise is good for your overall health and is an important part of managing diabetes^[26]. However, exercise can lower your blood sugar, so you should always measure your blood sugar levels before and after activity^[22][26]. You may need to eat more carbohydrates and reduce your insulin dose to prevent dangerously low blood sugar during exercise^[22].

Education and Support

Diabetes self-management education and support can help you learn practical skills, gain confidence, and get the support you need^[24]. Everyone with type 1 diabetes can benefit from this education, whether newly diagnosed or living with it for years. You should be offered a free group course or online course within one year of being diagnosed^[19].

Disease-Modifying Therapy

In November 2022, the U.S. Food and Drug Administration approved Tzield™ (teplizumab-mzwv), the first disease-modifying therapy for delaying the onset of type 1 diabetes in people at risk of developing the disease^[14]. Studies have shown Tzield can delay the onset of type 1 diabetes for approximately 2 years^[14].

Possible Complications

Over time, high blood sugar can damage many parts of your body if type 1 diabetes is not well-managed^[3][4]. Potential complications include:

• Eye problems, including retinopathy (damage to blood vessels in the eye), cataracts, and glaucoma
• Foot problems, including ulcers and infections that can lead to gangrene
• Heart disease and stroke
• High blood pressure
• Kidney disease
• Oral health problems
• Neuropathy (nerve damage)
• Skin conditions

Close to half of people with type 1 diabetes will develop a serious complication over their lifetimes^[4]. However, consistently keeping your blood sugar within the recommended range can help prevent these problems. If you reach the first 20 years after diagnosis without any complications, your outlook is usually good^[4].

Research has shown that tight blood sugar control dramatically decreases the incidence of complications^[16]. The benefits of early, aggressive insulin therapy and intensive blood sugar control persist for several decades and are associated with a decrease in deaths from all causes^[16].

Hypoglycemia (low blood sugar) is another important concern. This occurs when your blood sugar drops too low, usually below 4 mmol/L^[22]. It can happen when you haven’t eaten enough carbohydrates or you’ve taken too much insulin. You’ll need to recognize symptoms like feeling hungry or dizzy, sweating, and shaking, and treat it quickly with a sugary drink or snack before it gets worse^[22].

People with diabetes are also two to three times more likely to have depression and are 20 percent more likely to be diagnosed with anxiety than those without diabetes^[4][13].

Living with Type 1 Diabetes

Living with type 1 diabetes requires daily attention, but many people with the condition lead full, healthy, and active lives^[1][7]. With the right tools, support, and information, you can manage the disease successfully.

Daily Management

Managing type 1 diabetes involves balancing your medications with your daily exercise routine and nutrition plan^[21]. You’ll need to:

• Check your blood sugar regularly
• Take insulin as prescribed
• Count carbohydrates in your food and drink
• Watch for signs of low or high blood sugar
• Change where you inject insulin or place your pump each time

It takes time and practice to learn how to make diabetes fit with the rest of your life, including family, work, school, holidays, and everything else^[24]. Over time, you’ll learn strategies that work best for you.

Building Your Support Team

Don’t face type 1 diabetes alone. Build a support team that includes healthcare providers, family, friends, and others who understand your disease^[26]. They can learn to recognize the signs of low blood sugar, help you seek medical care in emergencies, and encourage you as you deal with your symptoms and daily routines.

Connect with other people living with type 1 diabetes through support groups or online communities^[25][27]. Learning from others who have experienced the challenges can provide valuable insights and encouragement.

Important Considerations

Always carry something with you that will raise your blood sugar quickly, such as sugary drinks, sweets, or glucose tablets^[22]. Consider carrying medical identification, such as a bracelet or card, that lets people know you have type 1 diabetes^[22].

If you drive, you’ll need to follow specific rules about checking your blood sugar before driving and during your journey^[22]. You should tell the relevant authorities you have diabetes and take insulin, though this usually won’t stop you from driving.

Regular Check-Ups

You’ll have regular appointments with your diabetes care team, at least once a year and more often when first diagnosed^[19]. These check-ups will monitor your blood sugar control, check for complications, and provide support for your wellbeing and mental health.

Adults who have lived much of their life with type 1 diabetes emphasize several important lessons: Don’t let diabetes define who you are or limit what you can do, get involved in diabetes support groups, remember that it’s going to be OK, and don’t feel singled out because of the condition^[25].

• Pancreas