Type 1 Diabetes Explained: Causes, Symptoms, And Treatments

According to the Mayo Clinic, "type 1 diabetes, once known as juvenile diabetes or insulin-dependent diabetes, is a chronic condition in which the pancreas produces little or no insulin." It's an autoimmune condition in which the body attacks the insulin-producing cells of the pancreas. Although there's no cure for type 1 diabetes, it can be effectively managed with insulin injections. Poorly controlled type 1 diabetes, however, can lead to both high and low blood sugar levels. These in turn can cause a host of complications that can led to disability or early death.

Type 2 diabetes gets far more media attention than type 1, and there's good reason for that. Of the approximately 34.2 million Americans living with diabetes, only 1.6 million have type 1 (via the CDC). Approximately 200,000 of these individuals are under the age of 20. Each year, about 64,000 people are diagnosed. But rates of type 1 diabetes appear to be on the rise. Between 2001 and 2009, there was a 21% increase in type 1 diagnoses among people under age 20, and by 2050 an estimated 5 million Americans will have the condition (via Beyond Type 1).

Here's what you need to know about type 1 diabetes, including what symptoms to look for and what treatments are available. 

How the body regulates blood sugar

To understand type 1 diabetes, you need to know how the body oversees the very important task of controlling blood sugar levels. This is handled by the pancreas, a 6-inch gland located deep in the abdomen. More than 90% of the cells in the pancreas are dedicated to producing various digestive enzymes, while fewer than 5% of pancreatic cells handle production of the hormones that control blood sugar. These cells are known as islet cells or islets of Langerhans (via endocrineweb).

Beta islets produce insulin, while alpha islets produce its counterpart glucagon. When blood sugar levels are too high (for example, after eating a carb-heavy meal), beta cells release insulin into the bloodstream, which allows cells throughout the body to absorb the circulating glucose, which they can use to produce energy. Conversely, when blood sugar levels are too low, the alpha cells produce glucagon, which stimulates the liver to break down glycogen into glucose and release it into the blood. By working together, these two hormones keep blood sugar levels in a narrow healthy range (via endocrineweb).

In type 1 diabetes, the body attacks and destroys the beta islets, which prevents individuals from making insulin. Although the alpha islets aren't destroyed, most people with type 1 diabetes have alpha cell dysfunction. They tend to not release enough glucagon when blood sugar is low but also release inappropriately high amounts of it after a meal when blood sugar is high (via Insulin Nation).

How type 1 diabetes is different from other types of diabetes

Usually, if an article or health professional doesn't specify the type, they're referring to type 2 diabetes. That's because type 2 diabetes accounts for about 90% of all diabetes cases, while type 1 accounts for only about 5% to 10% (via the CDC). Type 1 diabetes is considered an autoimmune condition, whereas type 2 is caused by a combination of diet, lifestyle, and genetic factors (via the CDC). In type 1 diabetes, the pancreas beta cells are destroyed and it can't produce insulin, whereas in type 2 diabetes either the pancreas can't produce enough insulin to keep up with demand and/or the body's cells no longer respond to insulin the way they should. 

The symptoms of type 1 tend to appear suddenly (because the beta cells are being destroyed), whereas symptoms of type 2 often emerge slowly over time (via NIDDK). While type 1 diabetics must use insulin, type 2 diabetes can be managed in a variety of ways, including insulin, other medications, diet changes, and exercise. It may be possible to prevent type 2 diabetes or put it into remission, whereas that's not the case for type 1. Both, however, are equally serious conditions (via Diabetes UK).

Gestational diabetes develops in some women during pregnancy, although it usually resolves after the baby is born. Women who are diagnosed with gestational diabetes are considered a higher risk for developing type 2 diabetes (via the Cleveland Clinic).

Type 1 diabetes is a bit of a mystery

As mentioned above, type 1 diabetes is an autoimmune condition in which the body's immune system, which usually protects you from foreign invaders like viruses and bacteria, mistakenly begins attacking healthy tissue — in this case, the insulin-producing beta islet cells of the pancreas. What's still unclear, however, is why. What triggers the immune system to go haywire? Certain genes may increase a person's chances of developing type 1 diabetes, but researchers are also investigating environmental factors such as viral infections as a possible trigger (via JDRF).

While the underlying cause of type 1 diabetes is still unknown, a few risk factors have been identified. In addition to particular genes, a family history of type 1 diabetes slightly increases the likelihood someone will have the condition. Age is also a major risk factor. While type 1 diabetes can appear at any time, there are two peaks in its occurrence: between ages 4 and 7 and again between 10 and 14 (via the Mayo Clinic). Race is also a risk factor. According to the Centers for Disease Control and Prevention (CDC), "In the United States, whites are more likely to develop type 1 diabetes than African Americans and Hispanic/Latino Americans." As you can see, all of these risk factors are outside an individual's control, so there's nothing you can do to lower your chances of getting type 1 diabetes.

Diagnosing type 1 diabetes

Although type 1 diabetes is a chronic condition, it has a definite "start" when the immune system begins attacking the insulin-producing beta islet cells. As a result, symptoms often appear quickly and are the result of the body losing its ability to regulate blood sugar normally. Common signs and symptoms include increased thirst and extreme hunger, as well as frequent urination and unintended weight loss. Fatigue, weakness, irritability, mood changes, and blurred vision can also occur. Children who weren't previously struggling with bed wetting during the night may suddenly start having this issue (via the Mayo Clinic).

If a doctor suspects someone has type 1 diabetes, there are a number of tests that can confirm the diagnosis. A fasting glucose test is often the first step, as individuals with untreated diabetes have high blood glucose levels. Individuals may also be given an oral glucose tolerance test, in which they drink a sugar-laden solution and doctors check to see how the body responds. A glycated hemoglobin A1c test can also be performed, which gives health professionals an idea of what a person's blood sugar levels have been like over the past few months. An individual's levels of C-peptide may also be checked, as this is a good proxy for gauging how much insulin is circulating (via JDRF).

Managing type 1 diabetes

Once someone is diagnosed with type 1 diabetes, it becomes a lifelong condition. Although type 1 diabetes can't be cured, it can be managed. The goal of diabetes management is to spend as much time as possible with blood sugar levels within a healthy range, as both low blood sugar and especially high blood sugar levels can cause major health complications if experienced frequently. To do this, type 1 diabetics must check their blood sugar regularly throughout the day using an at-home blood sugar monitor. This device requires a tiny sample of blood and gives a real-time readout of a person's blood sugar levels. 

Type 1 diabetics administer insulin to keep blood sugar levels in check (via the CDC). According to the Mayo Clinic, the ideal blood sugar range before a meal is 80–130 mg/dL. Two hours after eating, blood sugar should be no higher than 180 mg/dL. The Mayo Clinic noted that eating a healthy diet and learning to count the carbohydrates in a meal (so that a person can administer the right amount of insulin) is valuable. Getting enough physical activity is also important, as this naturally lowers blood sugar levels.

It's also important that people with type 1 diabetes get education about their condition. And if you have type 1 diabetes you should wear a medical alert bracelet or necklace — and always have a source of sugar with you in case of extremely low blood sugar (via American Family Physician).

Insulin options

Because people with type 1 diabetes can't make their own insulin, they must take insulin daily. But while your body only makes one type of insulin, there are a few synthetic options, which are classified based on how fast and how long they act. Rapid-acting insulin is usually taken right before a meal and starts to work in just 15 minutes, but only lasts two to four hours. Regular or short-acting insulin takes about 30 minutes to start working and lasts three to six hours. Long-acting and ultra-long-acting provide a stable supply of insulin for 24 to 36 hours. Most type 1 diabetics will take a "combination of insulins" (via the CDC).

There are several ways insulin can be administered. It's most often injected under the skin using a syringe or an insulin pen. An insulin pen uses an insulin-filled cartridge and the user simply "dials in" the amount of insulin they want to inject. Special insulin inhalers can also be used to administer aerosolized rapid-acting insulin. Finally, an insulin pump is a small device that delivers insulin at regular intervals through a semi-permanent plastic tube inserted under the skin (via the CDC).

For many years insulin was harvested from the pancreases of pigs and cows. By the early 1980s, however, manufacturers began making biosynthetic human insulin. Using recombinant DNA technology, manufacturers insert human insulin genes into E. coli bacteria, causing the bacteria to produce human insulin (via the National Library of Medicine).

Monitoring type 1 diabetes long-term

In addition to regular blood sugar monitoring and insulin injections at home, type 1 diabetes must be monitored by a team of health professionals. As the Centers for Disease Control and Prevention explained, this team can include "your primary care doctor, endocrinologist (a doctor who treats diabetes and other hormone problems), foot doctor, eye doctor, dentist, pharmacist, nurse, dietitian, and diabetes educator." These providers can help patients fine-tune their at-home management and check for and address diabetes-related complications.

The most important tool for monitoring type 1 diabetes is the hemoglobin A1c (HbA1c) test. Hemoglobin is a protein in red blood cells that allows them to carry oxygen throughout your body. As glucose builds up in your blood it will bind to hemoglobin. An HbA1c test measures how much glucose is attached to hemoglobin. Since red blood cells have a lifespan of about two to three months, the HbA1c test gives doctors a valuable glimpse into the past. 

HbA1c is expressed in terms of percentages. An HbA1c of 5% corresponds to an average glucose level of 97 mg/dL, while 7% corresponds to 152 mg/dL. Normal HbA1c values range between 4% and 5.6%. People with poorly managed diabetes may have an HbA1c as high as 14 (average glucose of 355 mg/dL). Individuals with diabetes should aim to keep their HbA1c below 7% (via WebMD).

High blood sugar

Although the goal of managing type 1 diabetes is to keep blood sugar levels in a healthy range, that's sometimes easier said than done. If blood sugar levels rise above 180 mg/dL, this is considered high blood sugar (hyperglycemia), as noted by the Cleveland Clinic. Symptoms of hyperglycemia include fatigue, headache, increased thirst, frequent urination, and blurred vision. Extremely high blood sugar levels or hyperglycemia that isn't treated and persists for a long time can cause nausea and vomiting, shortness of breath, dry mouth, fruity-smelling breath, and coma. Since type 1 diabetics can't make their own insulin, they must administer synthetic insulin to bring these high blood sugar levels under control. People with diabetes who frequently experience hyperglycemia are at much greater risk of long-term complications.

For type 1 diabetics, the most common cause of hyperglycemia is not taking enough insulin to counter the effects of a meal. Illness, injury, and emotional stress can also trigger hyperglycemia because cortisol and other hormones produced in response to these situations also raise blood sugar levels (via the Mayo Clinic). 

Diabetics may experience hyperglycemia in the morning because of the so-called dawn phenomenon. According to the Mayo Clinic, "The dawn phenomenon ... is the term used to describe an abnormal early-morning increase in blood sugar ... usually between 2 a.m. and 8 a.m." Researchers believe early-morning hyperglycemia occurs because hormones secreted during sleep, including growth hormone, cortisol, glucagon, and epinephrine, raise blood sugar levels by temporarily increasing insulin resistance. 

Low blood sugar

At the other end of the spectrum, low blood sugar (hypoglycemia) can also be a problem (via the Mayo Clinic). A blood sugar level of less than 70 mg/dL is considered low. Blood sugar levels can dip too low because an individual took too much insulin, didn't eat enough, or exercised too heavily. Hypoglycemia symptoms can vary from person to person, and one individual may begin experiencing symptoms at a higher or lower blood sugar threshold than another. In fact, some individuals don't experience any symptoms, so it's important to closely monitor blood sugar levels. 

Early warning signs of hypoglycemia include shakiness, dizziness, sweating, hunger, rapid heartbeat, confusion and difficulty concentrating, headache, anxiety, and irritability. If hypoglycemia occurs during sleep, a person may experience night sweats, nightmares, and tiredness or confusion upon waking. Signs of severe hypoglycemia include clumsy or jerky movements, inability to eat or drink, slurred speech, drowsiness, seizures, unconsciousness, and, in rare instances, death. Because of hypoglycemia's effects on cognition, it's important that a diabetic's friends and family be familiar with the warning signs of and treatment for hypoglycemia.

Hypoglycemia is treated by raising blood sugar levels. This is usually done by eating or drinking a simple sugar, such as juice, hard candies, or a teaspoon of straight sugar. Glucose tablets or gels can also be used. Emergency glucagon injections can be given by someone else if an individual is so hypoglycemic that they can't eat or drink (via the Mayo Clinic).

Diabetic ketoacidosis is a medical emergency

One potential complication of poorly managed type 1 diabetes that can quickly become a medical emergency is a condition known as diabetic ketoacidosis. If there isn't enough circulating insulin to help glucose enter the cells, blood sugar levels rise and the body will begin breaking down stored fat to use as an alternative fuel source. This breakdown produces acids known as ketones. At high levels, these ketones make the blood too acidic, which can interfere with many organ systems. Symptoms of diabetic ketoacidosis often come on suddenly, and for some individuals the appearance of the condition is what leads to an initial diabetes diagnosis (via the Mayo Clinic). 

Symptoms are the same as hyperglycemia, including excessive thirst, frequent urination, nausea and vomiting, abdominal pain, weakness, fruity-smelling breath, and confusion. At-home test kits will show high blood sugar levels and ketones in the urine.

Type 1 diabetics are the most at risk of diabetic ketoacidosis, according to the Mayo Clinic. The condition is often triggered by an illness, as hormones released when you're fighting something off can interfere with insulin's effects. Pneumonia and UTIs are common culprits. Other potential triggers include skipping insulin doses, not taking enough insulin, a malfunctioning insulin pump, emotional trauma, heart attack, pregnancy, alcohol or drug use (especially cocaine), and the use of certain medications. Diabetic ketoacidosis is treated in an emergency room or hospital with fluid and electrolyte replacement and insulin to bring blood sugar levels back under control.

Long-term complications

All long-term complications of type 1 diabetes (and diabetes in general) stem from poorly managed blood sugar levels. The more time a diabetic spends outside of a healthy blood sugar range, the more likely complications will eventually appear. In general, high blood sugar increases risk for complications more than low blood sugar. It usually takes at least 10 years for these complications to become apparent. Large amounts of sugar in the blood physically damage both small and, eventually, larger blood vessels. Diabetes complications are the result of this damage. Damage to the small vessels of the eyes can lead to retinopathy (damage to the retina), cataracts, and eventually blindness (via endocrineweb). 

The small vessels inside the kidneys can also be affected, leading to kidney disease and kidney failure. Nerves can be affected when the blood vessels supplying them are damaged, which can lead to loss of sensation, particularly in the feet, noted endocrineweb. Damage to larger blood vessels makes it easier for plaque to build up, which in turn increases risk for heart disease. Both type 1 and type 2 diabetes are considered major risk factors for heart disease, the leading cause of death in the United States (via the CDC). According to WebMD, "patients diagnosed with diabetes before age 10 had a 30 times greater risk of serious heart problems. Risk levels were about six times higher for people whose type 1 diabetes was diagnosed between ages 26 and 30."

Does type 1 diabetes affect life expectancy?

Before the discovery of insulin in 1921, type 1 diabetes was a death sentence. According to the American Diabetes Association (ADA), once diagnosed, individuals only lived for a few years at most. The only thing doctors could do was put diabetics on a strict diet with almost no carbohydrates in an effort to keep blood sugar levels down. But this only bought patients some time, and often the diet (which could be as few as 450 calories a day) would lead to death by starvation.

Although the advent of injectable insulin gave type 1 diabetics a new lease on life, research suggests that their lives are still cut short because of the condition. A 2015 study published in the Journal of the American Medical Association and reported on by WebMD concluded that men with type 1 diabetes live an average of 11 fewer years compared to their non-diabetic counterparts, while women with type 1 diabetes lose an average of 13 years. 

Most of this was attributed to diabetics' increased risk for heart disease, although episodes of severe hypoglycemia or diabetic ketoacidosis are also to blame for these sobering statistics. But according to another study published in the same journal, intensive management of blood sugar levels can reduce the risk of premature death by about a third. As study co-author Dr. Samuel Dagogo-Jack explained, "Across the board, individuals who had better glucose control due to intensive therapy had increased survival."

Pancreas transplant

Since a type 1 diabetic's pancreas can't produce insulin on its own, why not simply swap it out for a fully functional one? In fact, pancreas transplantation is an option, but one that's rarely used. As the Mayo Clinic explained: "Most pancreas transplants are done to treat type 1 diabetes. A pancreas transplant offers a potential cure for this condition. But it is typically reserved for those with serious complications of diabetes because the side effects of a pancreas transplant can be significant." Many of these side effects stem from having to take anti-rejection medications the rest of your life after receiving a donated organ. These medications, while absolutely necessary, can cause bone thinning, high cholesterol, high blood pressure, digestive upset, weight gain, and decreased ability to defend against infections. As with all surgical procedures, a pancreas transplant comes with certain post-operative risks, including blood clots, heavy bleeding, infections, urinary problems, and failure of the transplanted pancreas.

Pancreas transplants may be done alone or in conjunction with a kidney transplant. They are usually only considered for patients with very poorly controlled type 1 diabetes, as well as those with extensive kidney damage or who have reactions to injected insulin. According to the Health Resources and Services Administration (HRSA), only about 1,000 pancreas transplants (with or without kidney transplantation as well) are performed each year. Depending on the type of pancreas transplant surgery performed, rejection rates range from 11.2% to 18%. 

Future stem cell therapies for type 1 diabetes

Although type 1 diabetes is considered an incurable condition except in the case of a successful pancreas transplant (which carries its own significant risks), researchers are working hard to change that. For several decades, insulin-producing beta cells from donated pancreases have been implanted in the pancreases of type 1 diabetics (via UCSF). Although less risky than transplanting an entire pancreas, this procedure still requires lifelong use of immunosuppressants, and the beta cells don't always survive long-term. Also, there simply aren't enough donated pancreases to meet widespread demand. 

However, scientists have begun working with stem cells, with the goal of finding a way to coax them to differentiate into beta cells. These stem cell lines could produce an unlimited supply of beta cells for transplant (via Nature).

While experiments using stem cells to give type 1 diabetics back the ability to produce their own insulin have been limited to petri dishes and animals, in 2021 a clinical trial of stem cell-derived beta cells was conducted on a human. At the 90-day mark, the individual had cut down on the amount of insulin he had to inject daily by 91% (via USA Today). If scientists can discover how to encourage adult somatic stem cells to differentiate into beta islets, then an individual's own stem cells could be used (known as an autologous transplant). This would mean that immunosuppressants wouldn't be needed (via the Cleveland Clinic).