How are type 1 and 2 diabetes different

The basics

Diabetes mellitus is a common and serious medical problem.

An estimated 30 million people in the U.S. had diabetes in 2015. That’s almost 1 in 10 Americans. Diabetes is also a global problem, affecting 422 million people or 8% of the world’s population as of 2014.

Diabetes causes levels of sugar (glucose) in the blood to be higher than is safe.

There are four main types of diabetes:

• Type 1 diabetes (T1D)

• Type 2 diabetes (T2D)

• Gestational (diabetes that is diagnosed in pregnancy)

• Other rare types of diabetes (for example, diabetes related to cystic fibrosis or medications)

Type 2 diabetes is by far the most common, affecting about 95% of all people with diabetes. Many people with Type 2 diabetes have a family history of diabetes, but with healthy lifestyle changes, it can be prevented or slowed down.

Type 1 diabetes affects fewer than 5% of people with diabetes. It is usually diagnosed in childhood or the teenage years.

Here’s a guide to the differences between Type 1 and Type 2.

Table of contents

Why trust us

Dr. Kevin Hwang has been treating patients with acute and chronic medical problems since 2005 as a board-certified internal medicine physician. He also conducts research and teaches medical students and residents at UTHealth McGovern Medical School in Houston.

Do you have diabetes?

Do you have diabetes? If not, you may know somebody who does. Or maybe you’re worried about your blood sugar tests and think you might have diabetes? This guide is for you.

Diabetes is an energy-processing problem. This means that it affects how your body uses glucose for energy. The underlying problem in diabetes has to do with a hormone called insulin, made in an organ in your abdomen called the pancreas.

In a person without diabetes, the pancreas makes enough insulin to allow the cells of your body to pull glucose (sugar) from your bloodstream to use for energy.

In diabetes, either the pancreas does not produce enough insulin (Type 1 diabetes), or the body does not respond normally to insulin (Type 2 diabetes). This leads to high levels of glucose in the bloodstream (and not enough glucose in storage for when it’s needed). That’s why high blood glucose is the main sign of diabetes.

You might not have any symptoms in the early stages of diabetes. But as diabetes progresses, high blood glucose levels start to cause problems like:

• Frequent urination because your kidneys work overtime to flush out the excess glucose with large volumes of water

• Extreme hunger and thirst as a result of frequent urination

• Fatigue and weight loss because your body is in crisis and struggling to get energy

• Increased risk of infections like thrush (candidiasis) and slow healing skin.

Sometimes symptoms come on slowly over time. Other times, they can make you very sick very suddenly — especially if you don’t know you have diabetes.

Testing for diabetes

Diagnostic tests

There are several different blood tests for diabetes according to the American Diabetes Association. These tests are used to diagnose diabetes and monitor how diabetes is responding to treatment. The same blood tests are used for Type 1 diabetes and Type 2 diabetes. The tests will not tell you which type of diabetes you have. Only your provider can do that, and the diagnosis is based on your:

• Symptoms

• Risk factors

• Medical history

• Family history

The fasting blood glucose test

Fasting blood glucose is the glucose level in your blood when you haven’t had anything to eat or drink except water for 8 to 12 hours (usually overnight). In some situations, this test will need to be repeated to confirm whether you have diabetes.

The oral glucose tolerance test

This test is also done after you haven’t had anything to eat or drink except water for 8 to 12 hours. Then you drink a standard-strength, sweetened drink, and your blood glucose is checked 2 hours later.

The hemoglobin A1C test

Sometimes known simply as A1C, this test measures how high your blood glucose has been for the past 2 to 3 months. You don’t need special preparation for this test, so it can be done even on a full stomach.

Most people only need to have one of these three tests done to find out if they have diabetes. However, some people may need to get more than one test done for their provider to be sure.

Certain medications, like beta blockers, diuretics, and antidepressants, can interfere with both the fasting blood glucose and the oral glucose tolerance test.

Type 1 vs. type 2: What are the differences?

Type 1 diabetes

What is it?

In Type 1 diabetes, your immune system destroys the cells in your pancreas that make insulin. As a result, the pancreas does not produce insulin. Without insulin, blood glucose levels rise, which is the main abnormality health providers look for to diagnose diabetes. People with Type 1 diabetes need to inject insulin into their bodies to replace or copy their natural insulin.

When does it usually start?

Most people with Type 1 diabetes are diagnosed when they are children or young adults.

How is it treated?

People with Type 1 diabetes need to take insulin from the very beginning of the disease. In other words, insulin treatment is needed for survival. Anyone taking insulin needs to monitor their blood glucose levels regularly to be able to match the insulin they need to the insulin they take.

• Insulin injections: Most people with Type 1 diabetes use either a syringe and needle, or a prefilled injection pen to inject insulin into fatty areas under their skin. Different types of insulin last for different lengths of time. Short-acting insulin starts to work within 15 minutes and lasts for 2 to 4 hours. Other types of insulin act slowly over 6 hours, 12 hours, 24 hours, or even longer. There are many different options to match the insulin you take to your eating habits, your blood glucose readings, and your level of physical activity throughout the day.

• Insulin pump: Insulin pumpsare small, wearable, computerized, battery-powered devices that deliver a steady dose of insulin throughout the day through a small plastic tube (catheter) that stays under your skin. You can also activate the pump to deliver a boost of insulin, when needed. Newer pump systems use software and wireless technology to connect an insulin pump to a continuous blood glucose monitor, and automate insulin delivery in response to blood glucose levels.

• Inhaled insulin: Although it’s not common, another way to get insulin is to inhale it into your lungs using a special device. The insulin that is available in the inhalation device starts acting rapidly (within 12 minutes) but only lasts for a few hours. Inhaled insulin is not recommended for people with lung problems like asthma, chronic bronchitis, or emphysema.

Who gets it and why?

We don’t know exactly why some people get Type 1 diabetes and others don’t. It’s likely due to a combination of genes and environment. If you have a close relative with Type 1 diabetes, your risk of developing it is higher. Scientists continue to do research on whether certain infections during pregnancy and early infancy can trigger the pancreatic damage that leads to Type 1 diabetes.

Why does it matter?

Put simply, untreated diabetes can kill you. If somebody with Type 1 diabetes goes a long time without adequate insulin treatment, they can get a life-threatening complication called diabetic ketoacidosis (DKA). Symptoms include:

• Shortness of breath

• Rapid heartbeat

• Fruity taste or smell on the breath

• Confusion

• Coma

DKA needs to be treated as an emergency in the hospital.

Even without an emergency such as DKA, blood glucose levels that are higher than normal can also cause many health problems in the long term. High blood glucose damages blood vessels and nerves in the body. Common health problems that people with diabetes have include:

• Eye damage, leading to blindness

• Kidney damage, leading to kidney failure

• Neuropathy (nerve damage), leading to pain and numbness in hands and feet

• Increased (doubled) risk of heart disease and death from heart problems

• Increased risk of strokes (and disability from strokes) and death

Keeping your blood glucose levels within normal range as much as possible will help prevent these complications.

How common is it?

Type 1 diabetes is not as common as Type 2. Of all people with diabetes, only about 5% have Type 1 diabetes.

Type 2 diabetes

What is it?

Type 2 diabetes is the most common form of diabetes. In Type 2 diabetes, the pancreas produces insulin, but the body does not respond to it in the normal way. This is the main difference between T1D and T2D.

Normally, insulin allows your body to use glucose from your bloodstream for energy. But in Type 2 diabetes, your body starts to ignore the insulin, and glucose stays in your bloodstream instead of being used as energy. This is called “insulin resistance,” and like in Type 1 diabetes, it causes high levels of blood glucose (even though insulin levels are usually normal).

In the early stages of Type 2 diabetes, the pancreas goes into overdrive and pumps out more and more insulin to try to overcome insulin resistance. Over time, the pancreas gets worn out and struggles to produce insulin. That's why some people with Type 2 diabetes for a long time eventually need to take insulin injections — just like those with T1D.

When does it usually start?

Type 2 diabetes usually starts in adulthood. However, kids and teens who are overweight can also develop Type 2 diabetes.

How is it treated?

The keys to treating Type 2 diabetes are eating healthy, staying physically active, and maintaining a healthy body weight.

• Healthy nutrition: Eat a variety of vegetables and fruits, whole grains, fat-free or low-fat dairy foods, and lean proteins. Watch your portion sizes and try not to get “empty” calories from sugary foods and drinks.

• Physical activity: Staying active throughout the day and getting regular exercise will lower your blood glucose as your muscles use glucose for fuel. Aim for 150 minutes of exercise per week, or 30 minutes 5 days a week.

• Weight loss: Eating healthier and exercising more will get you on the right track to losing excess pounds, which helps to lower blood glucose levels and slow down how quickly Type 2 diabetes progresses.

In addition to making lifestyle changes, many people with Type 2 diabetes also take medications to lower their blood glucose. The most common types of medications used for Type 2 diabetes are:

• Metformin (pill)

• Sulfonylureas (pill)

• GLP-1 agonists (injections)

• DPP-4 inhibitors (pill)

• SGLT2 inhibitors (pill)

• Insulin (injections)

Examples of medications and their estimated monthly costs are listed below:

*As of April 2020

You can read more about treatments for diabetes in our guides here:

• Oral medications

• Injectable medications

Metformin is recommended as the first-choice treatment for most people with Type 2 diabetes. Other medications can be added on top of metformin, if needed.

Who gets it and why?

You’re more likely to develop Type 2 diabetes if you have any of the following risk factors:

• Age 45 years of age or older

• Overweight (BMI of 25 or higher) or obesity

• High blood pressure

• Exercise fewer than three times a week

• A diagnosis of prediabetes 

• A parent or sibling with Type 2 diabetes

• African American, Hispanic/Latino American, American Indian, Asian American, or Pacific Islander ethnicity

For women only:

• A diagnosis of polycystic ovary syndrome (PCOS)

• Diabetes during pregnancy

• Gave birth to a baby that weighed more than 9 pounds

Why does it matter?

Hyperosmolar hyperglycemic state (HHS) is a life-threatening condition that happens in Type 2 diabetes when blood glucose levels are very high. It is similar in many ways to DKA, the medical emergency of T1D. Symptoms include:

• Increased thirst and urination

• Weakness

• Dry mouth

• Rapid heartbeat

• Confusion

• Coma or death

HHS is often triggered by an infection (like pneumonia) or another illness (like a heart attack or stroke). HHS needs to be treated in the hospital as an emergency. Type 2 diabetes also causes all the same long-term complications as Type 1 diabetes.

How common is it?

Approximately 90% to 95% of people with diabetes have Type 2 diabetes.

Other causes of diabetes

Although more than 95% of people with diabetes have Type 2 or Type 1, there are some other rare causes of diabetes:

• Gestational diabetes: This is diabetes that develops when you are pregnant. After the baby is born, this diabetes may go away or remain. Having gestational diabetes increases the risk of developing Type 2 diabetes later.

• Drug-induced diabetes: This occurs when a medication increases your blood glucose levels to the point of diabetes. Examples of medications that can cause diabetes include:

  • Glucocorticoids (such as prednisone)

  • Thiazide diuretics

  • Antipsychotic medications

  • Some HIV medications

  In some cases, the diabetes goes away after stopping the medication. In other situations, diabetes may continue as a permanent condition.

• Monogenetic diabetes: This is a rare form of diabetes that is caused by a mutation (or change) in a single gene. The main forms of monogenetic diabetes are neonatal diabetes mellitus (NDM), which affects newborns, and maturity-onset diabetes of the young (MODY), which usually affects teenagers or young adults.

• Cystic fibrosis-related diabetes: People with cystic fibrosis — a chronic, inherited lung disease — often have problems with high blood glucose, which can lead to full-blown cystic fibrosis–related diabetes (CFRD). CFRD has features of both Type 1 and Type 2 diabetes. The pancreas produces some insulin but not enough, and the body does not respond normally to insulin. The American Diabetes Association recommends insulin as the best treatment for CFRD.

• Latent autoimmune diabetes in adults: This is a form of diabetes that is similar to Type 1 diabetes, where the immune system attacks the cells in the pancreas that make insulin, but in latent autoimmune diabetes in adults, the process is much slower. People with this type of diabetes do not need to take insulin at first but will eventually need to do so.

• Post-transplant diabetes: Individuals who receive an organ transplant usually have high blood glucose levels immediately after the surgery. After leaving the hospital, some people continue to have glucose levels that meet the definition of diabetes. The drugs used to prevent rejection of the organ (immunosuppressants) are partly to blame for post-transplant diabetes.

• Stress-induced hyperglycemia: This is a special situation where blood glucose levels temporarily rise to diabetes levels during severe, acute illnesses, such as life-threatening infections. It is quite commonly seen in unwell, older people who are admitted to the hospital.

Keep in mind

Some people, especially young adults, can have features of both Type 1 and Type 2 diabetes. In fact, a recent study published in The Lancet, suggested that diabetes is a group of many very different diseases that have all been given the same name because they all share the same blood test abnormality: high blood glucose.

The Finnish team behind the research suggested that there are 5 different diabetes disease types, not two:

1. Severe autoimmune diabetes: This is what we currently call Type 1 diabetes. People are young, have insulin deficiency, and test positive for diabetes autoantibodies (a sign that the body is attacking its own pancreas cells). This is probably the rarest form of diabetes. Between 6% and 15% of diabetics have this type.

2. Severe insulin-deficient diabetes: In this type, people are young and have insulin deficiency but do not test positive for diabetes autoantibodies. About 9% to 20% of the study population were affected.

3. Severe insulin-resistant diabetes: This type affected 11% to 17% of the study population.

4. Mild obesity-related, insulin-resistant diabetes: This was the second-most common type of diabetes, affecting just under one quarter of the population studied.

5. Mild age-related, insulin-resistant diabetes: This was the most common form of diabetes seen in the study, affecting almost 50% of the Swedish and Finnish population studied.

American Diabetes Association. (2019). 9. Pharmacologic Approaches to Glycemic Treatment: Standards of Medical Care in Diabetes—2019 Diabetes Care. 42(Suppl. 1): S90–S102.

Centers for Disease Control and Prevention. (2020). National Diabetes Statistics Report. Retrieved 4/9/2020 from https://www.cdc.gov/diabetes/pdfs/data/statistics/national-diabetes-statistics-report.pdf.

BMJ Best Practice. (2020). Type 1 Diabetes Mellitus. Retrieved 4/9/2020 from http://bestpractice.bmj.com/topics/en-us/25/aetiology.

Marik, P.E. & Bellomo, R. (2013). Stress hyperglycemia: an essential survival response!. Critical Care. 17(2):305.

The National Institute of Diabetes and Digestive and Kidney Diseases. (2016). What is Diabetes?. Retrieved 4/9/2020 from https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes.

The National Institute of Diabetes and Digestive and Kidney Diseases. (2016). Risk Factors for Type 2 Diabetes. Retrieved 4/9/2020 from https://www.niddk.nih.gov/health-information/diabetes/overview/risk-factors-type-2-diabetes

The National Institute of Diabetes and Digestive and Kidney Diseases. (2017). Monogenic Diabetes (Neonatal Diabetes Mellitus & MODY). Retrieved 4/9/2020 from https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/monogenic-neonatal-mellitus-mody.

Pasquel, F.J. & Umpierrez, G.E. (2014). Hyperosmolar Hyperglycemic State: A Historic Review of the Clinical Presentation, Diagnosis, and Treatment. Diabetes Care. 37 (11) 3124–3131.

Stenström, G., Gottsäter, A., Bakhtadze, E., et al. (2005). Latent Autoimmune Diabetes in Adults: Definition, Prevalence, β-Cell Function, and Treatment. Diabetes. 54(suppl 2): S68–S72.

World Health Organization. (2018). Diabetes. Retrieved 4/9/2020 from https://www.who.int/news-room/fact-sheets/detail/diabetes.

GoodRx Health has strict sourcing policies and relies on primary sources such as medical organizations, governmental agencies, academic institutions, and peer-reviewed scientific journals. Learn more about how we ensure our content is accurate, thorough, and unbiased by reading our editorial guidelines.

Was this page helpful?

Take Control of Diabetes!

Sign up for our GoodRx Diabetes Newsletter to receive up-to-date information on the latest medications, diet tips, and savings that are most relevant to you.

By signing up, I agree to GoodRx's Terms and Privacy Policy, and to receive marketing messages from GoodRx.