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Type 1 and type 2 diabetes both occur when the body cannot properly store and use glucose, which is essential for energy. Sugar, or glucose, collects in the blood and does not reach the cells that need it, which can lead to serious complications.

Type 1 diabetes usually appears first in children and adolescents, but it can occur in older people, too. The immune system attacks the pancreatic beta cells so that they can no longer produce insulin. There is no way to prevent type 1 diabetes, and it is often hereditary. Around 5 percent of people with diabetes have type 1, according to the Centers for Disease Control and Prevention (CDC).

Type 2 diabetes is more likely to appear as people age, but many children are now starting to develop it. In this type, the pancreas produces insulin, but the body cannot use it effectively. Lifestyle factors appear to play a role in its development. According to the CDC, around 90–95 percent of people with diabetes have this type.

Both types of diabetes can lead to complications, such as cardiovascular disease, kidney disease, vision loss, neurological conditions, and damage to blood vessels and organs.

The CDC estimate that over 30 million people in the United States probably have diabetes, but 25 percent of them do not know they have it.

Another type is gestational diabetes. This occurs in pregnancy and typically resolves after childbirth, but some people then develop type 2 diabetes later in life.

This article will look at the differences and similarities between type 1 and type 2 diabetes.

Type 1 and type 2 have different causes, but they both involve insulin.

Insulin is a type of hormone. The pancreas produces it to regulate the way blood sugar becomes energy.

Type 1 diabetes

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Type 1 diabetes often affects young people.

In this type, scientists believe that the immune system mistakenly attacks the pancreatic beta cells, which produce insulin. They do not know what causes this to happen, but childhood infections may play a role.

The immune system destroys these cells, which means that the body can no longer make enough insulin to regulate blood glucose levels. A person with type 1 diabetes will need to use supplemental insulin from the time they receive the diagnosis and for the rest of their life.

Type 1 often affects children and young adults, but it can happen later in life. It can start suddenly, and it tends to worsen quickly.

Risk factors include:

  • having a family history of diabetes
  • being born with certain genetic features that affect the way the body produces or uses insulin
  • some medical conditions, such as cystic fibrosis or hemochromatosis
  • possibly, exposure to some infections or viruses, such as mumps or rubella cytomegalovirus

Type 2 diabetes

In type 2 diabetes, the body's cells start to resist the effects of insulin. In time, the body stops producing enough insulin, so it can no longer use glucose effectively.

This means glucose cannot enter the cells. Instead, it builds up in the blood.

This is called insulin resistance.

It can happen when the person always or often has high blood glucose. When the body's cells are overexposed to insulin, they become less responsive to it, or maybe they no longer respond at all.

Symptoms may take years to appear. People may use medications, diet, and exercise from the early stages to reduce the risk or slow the disease.

In the early stages, a person with type 2 diabetes does not need supplemental insulin. As the disease progresses, however, they may need it to manage their blood glucose levels in order to stay healthy.

Risk factors for type 2 diabetes include:

  • having a family member with type 2 diabetes
  • having obesity
  • smoking
  • following an unhealthful diet
  • a lack of exercise
  • the use of some medications, including some anti-seizure drugs and some medications for HIV

People from certain ethnic groups are more likely to develop type 2 diabetes. These include Black and Hispanic people, Native American Indians and Native Alaskans, Pacific Islanders, and some people of Asian origin, according to the CDC.

Genetic and environmental factors may trigger both type 1 and type 2 diabetes, but many people may be able to avoid type 2 by making healthful lifestyle choices.

Research has also suggested that some other environmental factors might play a role.

Vitamin D

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Studies have suggested that vitamin D may help prevent both type 1 and type 2 diabetes.

Low levels of vitamin D may play a role in the development of both type 1 and type 2 diabetes, according to some studies.

A review published in 2017 suggests that when a person lacks vitamin D, certain processes in the body, such as immune function and insulin sensitivity, do not work as well as they should. According to scientists, this may increase a person's risk of diabetes.

The primary source of vitamin D is exposure to sunshine. Food sources include oily fish and fortified dairy products.

Breastfeeding

Some researchers have suggested that giving an infant only breastmilk, even for a short time, might help prevent type 1 diabetes in the future.

A review published in 2012 concluded that there might be "weak protective associations" between exclusively breastfeeding and type 1 diabetes. However, there was not enough evidence to prove that a link exists.

A person with diabetes may experience symptoms and complications due to inadequate levels of blood sugar.

Other aspects of metabolic syndrome also occur alongside type 2 diabetes, including obesity, high blood pressure, and cardiovascular disease. Inflammation appears to play a role.

The chart below outlines the symptoms and complications of type 1 and type 2 diabetes before and at the onset of the condition.

Type 1Type 2
Before onsetBMI within a healthy range (19–24.9)BMI above the healthy range (25 or over)
At onsetAppearance over several weeks of:
increased thirst and urination
increased hunger
blurry vision
tiredness and fatigue
numbness or tingling in hands and feet
sores or wounds that take a long time to heal
unexplained weight loss
Development over several years of:
increased thirst and urination
increased hunger
blurry vision
tiredness and fatigue
numbness or tingling in hands or feet
sores or wounds that take a long time to heal
unexplained weight loss
ComplicationsRisk of:
cardiovascular disease, including a risk of heart attack and stroke
kidney disease and kidney failure
eye problems and vision loss
nerve damage
problems with wound healing
ketoacidosis
Risk of:
cardiovascular disease, including a risk of heart attack and stroke
kidney disease and kidney failure
eye problems and vision loss
nerve damage
problems with wound healing, which can lead to gangrene and the need for an amputation
ketoacidosis

Hyperglycemia

If a person's blood sugar is too high, they may experience the signs and symptoms of hyperglycemia and long-term complications, such as vision loss, cardiovascular disease, and organ failure.

According to the American Diabetes Association (ADA), when a person has hyperglycemia, they may experience the following:

  • frequent urination
  • increased thirst

This can lead to ketoacidosis, a potentially life-threatening condition that needs urgent medical attention.

Symptoms include:

  • difficulty breathing
  • a fruity smell on the breath
  • nausea and vomiting
  • a dry mouth
  • coma

Click here to learn more about hyperglycemia.

Hypoglycemia

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People with diabetes need to test their blood sugar levels regularly.

Hypoglycemia is when blood sugar levels are too low. This can result in diabetes if the person uses more insulin or drugs that cause the body to produce insulin than they need.

Early symptoms include:

  • sweating, chills, and a pale face
  • feeling shaky, nervous, and anxious
  • rapid heartbeat
  • feeling dizzy and lightheaded
  • nausea
  • feeling weak and tired
  • headache
  • tingling

A person should take a glucose tablet, a candy, or a sweet drink to relieve the symptoms and prevent the problem from getting worse. Follow this with a protein-based food, such as peanut butter.

Without treatment, the person may experience:

  • seizures
  • loss of consciousness
  • coma

This can be life-threatening and needs immediate medical attention.

A person with diabetes should carry a medical ID so that others will know what to do if a problem occurs.

Find out more here about hypoglycemia.

The onset of type 1 diabetes tends to be sudden. If symptoms are present, the person should see a doctor as soon as possible.

A person with prediabetes, which is the earliest stage of type 2 diabetes, and the early stages of type 2 will have no symptoms, but a routine blood test will show that blood sugar levels are high.

People with obesity and other risk factors for type 2 diabetes should have regular checks to ensure that their glucose levels are healthy. If tests show they are high, the person can take action to delay or prevent diabetes and its complications.

The following tests can assess for type 1 or type 2 diabetes, but they may not all be useful for both types:

Depending on the results, the doctor may diagnose diabetes or prediabetes.

The following table shows what type of results indicate diabetes:

A1C (%) FPG
(milligrams per deciliter (mg/dl)
OGTT
(mg/dl)
RPG
(mg/dl)
Diabetes6.5% or above126 or over200 or over200 or over
Prediabetes5.7–6.4%100–125140–199
Normalbelow 5.7%below 100below 140below 200

The ADA recommend regular screening for type 2 diabetes in people aged 45 years and above, or earlier for those with risk factors.

People can check their own blood glucose levels at home. Testing kits are available for purchase online.

There is no cure for diabetes, but treatment can help people to manage it and prevent it from getting worse. Here are some points about treating and managing diabetes.

Type 1Type 2
Possible cureCurrently no cure, but lifetime treatment can manage symptoms.
In time, gene therapy, regenerative medicine using stem cells, or pancreatic islet transplantation may become an option.
Currently no cure, but measures can slow progression and manage symptoms.
Gastric bypass may reduce symptoms in people with severe obesity.
Treatment with insulin and other drugsDaily insulin injections or using an insulin pump can provide insulin as needed through the day and night.
Other drugs, such as pramlintide, can stop glucose levels from rising too far.
Metformin can reduce the amount of sugar the liver produces.
SGLT2 inhibitors, DP-4 inhibitors, or alpha-glucosidase inhibitors (AGIs) can reduce blood sugar levels.
Meglitinides or sulfonylureas can increase insulin levels.
Thiazolidinediones (TZDs) can increase sensitivity to insulin.
Glucagon-like peptide-1 (GLP-1) agonists can increase insulin and reduce sugar levels.
Amylin analogs can reduce blood sugar by slowing digestion.
Additional drugs for people at high risk of cardiovascular disease and atherosclerosis.
Insulin in some cases.
Lifestyle treatments
Follow the treatment plan and the doctor's instructions regarding insulin and glucose testing.
Follow an active, healthful lifestyle to reduce the risk of cardiovascular disease and other health issues.
Pay attention to glucose levels when exercising.
Managing blood pressure and high cholesterol levels.
Follow the treatment plan and medical advice. Healthful diet
Regular exercise
Managing blood pressure and high cholesterol levels
Avoiding smoking
Knowing the signs of adverse effects and complications.
Avoiding complicationsFollow the treatment plan and know the signs of hypo and hyperglycemia and the complications of diabetes.
Wear a medical ID.
Take measures to avoid infections
Have regular eye tests
Check for wounds and seek early treatment
Know the signs of possible complications to be ready to take action.
Wear a medical ID.
Take measures to avoid infections.
Check for wounds and seek early treatment.
Have regular eye tests.
Follow a healthful diet and take exercise to manage cholesterol levels and high blood pressure and reduce cardiovascular risk.
PreventionIt is not yet possible to prevent type 1 diabetes.Follow a healthful diet with regular exercise. Avoid or quit smoking.
Follow a doctor's instructions if they diagnose prediabetes.

Scientists have been investigating whether immunosuppressant drugs — effective in treating conditions such as multiple sclerosis (MS) and rheumatoid arthritis — might help prevent or reverse type 1 diabetes. However, results so far have been inconclusive.

There is no cure for type 2 diabetes, although gastric bypass surgery, lifestyle, and medication treatment can result in remission.

Find out more here about non-insulin drugs for type 2 diabetes.

Diabetes is a serious condition.

It is not currently possible for a person to prevent type 1, but insulin and other drugs can help people to manage their symptoms and live a normal life.

While there may be a hereditary link for both types of diabetes, people can both reduce the risk and manage the progress of type 2 diabetes dramatically by following a healthful lifestyle with regular exercise.

Anyone with a diagnosis of prediabetes should also make healthful lifestyle choices, as this can reduce or eliminate the risk of type 2 diabetes developing.