What is the difference between type 1 and type 2 diabetes?

Parveen K. Verma, DO
Endocrinology Diabetes & Metabolism
The majority of people with diabetes have type 2 diabetes. This is a disease where there are two different deficits. The body is not making enough insulin, and the body is resistant to the effects of the insulin that it does make. Type 2 diabetes typically affects older individuals. Most people with type 2 have a genetic risk that's aggravated by lifestyle issues such as lack of activity or dietary habits.

Type 1 diabetes is an autoimmune disease. The body basically turns against its own pancreas and the cells that make insulin are no longer functional. So, these individuals always rely on insulin for treatment as opposed to type 2 patients, who can respond very successfully to pills or a combination of insulin and pills.

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Athena Philis-Tsimikas, MD
Endocrinology Diabetes & Metabolism
Type 1 diabetes is, like type 2, a disease of high blood sugar, but there are some differences. In this video, endocrinologist Athena Philis-Tsimikas, MD, of Scripps Health, explains how type 2 diabetes differs in its symptoms and treatment.
Anthony L. Komaroff, MD
Internal Medicine
Diabetes is marked by high levels of sugar in the blood. Most of the 24 million Americans with this condition have type 2 diabetes, which occurs when the body becomes resistant to the effects of insulin (the hormone made by the pancreas that enables cells to draw sugar from the blood for energy) and does not produce enough insulin to overcome the resistance. Although the exact cause of type 2 diabetes isn't clear, one thing is certain: excess body fat is the No. 1 risk factor. Type 1 diabetes is an autoimmune disorder that occurs when the immune system attacks the pancreas, destroying its insulin-producing cells.
Diabetes is a disease in which the levels of sugar (glucose) in your blood are too high. To understand the difference between type 1 and type 2 diabetes, you need to know what happens during normal metabolism. Most of the food you eat is broken down into glucose in your body. After digestion, the glucose enters your blood. Insulin, a hormone produced by your pancreas, helps get the glucose into your body's cells, where it can be used for energy. However, if you have type 1 diabetes (which affects 5% to 10% of people with the disease), your pancreas produces little or no insulin. You need to take insulin to live. Type 1 diabetes is usually diagnosed during childhood up through early adulthood.

If you have type 2 diabetes (which affects 90% to 95% of people with diabetes), your pancreas may produce enough insulin, but your body doesn't respond normally to the insulin by moving the glucose from the blood into your cells. As your disease progresses, your pancreas may produce less insulin. In type 1 diabetes, symptoms may come on suddenly. In type 2 diabetes, they may occur gradually or you may have no symptoms. Symptoms of both types of diabetes may include increased thirst and hunger, unexplained weight loss, fatigue and frequent urination.
Lori Maggioni
Nutrition & Dietetics

Diabetes is a metabolic disease in which the body does not produce or properly use insulin, a hormone needed to allow glucose to enter the cells. In other words, your body cannot use the fuel in the blood for energy.

Type 1 diabetes, previously known as juvenile diabetes or insulin-dependent diabetes, is a chronic condition in which the pancreas produces little or no insulin. Often diagnosed before the age of 30 but can occur at any time.

Type 2 diabetes is far more common than type 1 diabetes and occurs when the body becomes resistant to the effects of insulin or doesn't make enough insulin. It was previously known as noninsulin-dependent diabetes and is greatly affected by lifestyle choices.

Normal Values:

  • Normal fasting blood glucose (FBS) is <100 mg/dL
  • Normal Hemoglobin A1C is <5.7% (this shows the average of glucose over 60 - 90 days)

Diagnosis of Diabetes:

  • Diabetes is diagnosed if the FBS is >126 mg/dL or the A1C is >6.5%
  • Prediabetes is diagnosed if the FBS is 100 - 125 mg/dL or the A1C is 5.7 - 6.4%

Individuals with type 1 diabetes have no insulin production. With type 2 diabetes, the body still produces insulin but it is insufficient or ineffective. Approximately 90% of diabetes cases are type 2. Prediabetes is a condition when the blood glucose levels are higher than normal but not high enough for the diagnosis of diabetes.

Diabetes occurs when insufficient insulin production leads to abnormal metabolism of glucose, protein, and fat. Type 1, insulin dependent diabetes, is typically first seen in childhood. Type 2, insulin resistance, typically arises in adulthood, but there has been an increase in the condition being diagnosed in childhood. Although genetic predispositions impact both type 1 and type 2 diabetes, lifestyle factors such as poor diet and lack of physical activity account for 90-95% of type 2 diabetes.

From Good Kids, Bad Habits: The RealAge Guide to Raising Healthy Children by Jennifer Trachtenberg.

Good Kids, Bad Habits: The RealAge Guide to Raising Healthy Children

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Good Kids, Bad Habits: The RealAge Guide to Raising Healthy Children

When kids start going on TV binges or devouring fistfuls of cookies, it's easy to say, "They'll grow out of it." More likely, they're acquiring bad habits that could lead to childhood obesity and...
Dr. Michael Roizen, MD
Internal Medicine
Type I diabetes, sometimes called "juvenile diabetes" because the disease often begins in childhood, occurs when the body quits making insulin, the hormone necessary to metabolize sugar in your food and to regulate glucose levels in your blood. In contrast, Type II diabetes, or "adult-onset diabetes," usually develops after age thirty. Type II diabetes occurs when the cells in the body become insensitive to insulin. That is to say, the insulin receptors on the outside of each cell no longer react to the insulin molecule that signals the cell to break down glucose. Hence, blood glucose levels remain high because the sugar is not being taken in and broken down properly by the cell but, instead, is staying in the blood.
Jill A. Grimes, MD
Family Medicine

Type 1 diabetes, sometimes called juvenile onset diabetes, is caused by an absolute deficiency of insulin, which is why the treatment involves insulin injections.

The type of diabetes that is rapidly increasing these days is type 2 diabetes, also call adult onset diabetes. Type 2 diabetes is a different ballgame. Here, the problem is a resistance to insulin or a decreased production of insulin. Insulin is the key that opens the doors to cells, allowing sugar to come from the blood and move into the cell to be used as energy. When that door wont unlock (because of resistance to insulin), the sugar levels build up in the blood and eventually cause damage in many parts of the body -- the eyes, kidneys, nerves, blood vessels, and heart.

William Lee Dubois
Endocrinology Diabetes & Metabolism

So here’s the way I like to think about it:

Everything thing you eat is converted into glucose by your digestive system and dumped into your bloodstream. To get the glucose from the blood into each cell, your body uses a hormone called insulin.

You can think of insulin as a waitress whose job it is to deliver food to the cell’s table.

In those of us with Type-1 Diabetes, the waitress just stalked off the job. We can smell the food from the kitchen, but we sit at the table and starve.

In those of you with Type-2 Diabetes, the waitress is lazy. She brings the salad, sometimes the soup, but never the full meal. Your entrée, and those of your dinner guests, just pile up at the little window in front of the kitchen.

Likewise in our diabetic bodies, sugar piles up. The lack of insulin or the presence of lazy insulin (called insulin resistance) keeps the glucose from the cells where it is needed. As a result, the bloodstream becomes flooded with the sugar that can’t get into the cells, and that sets off a cascade of trouble.

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
People with type 1 diabetes make little or no insulin; people with type 2 can make insulin but there is usually a problem with it. Watch the animation to learn more about type 1 and type 2 diabetes.

Dr. Jack Merendino, MD
Endocrinology Diabetes & Metabolism
There is a lot of confusion on this simple question, partly because of the other names commonly used for these two conditions. Type 1 diabetes has often been called juvenile diabetes, and type 2 is frequently referred to as adult-onset diabetes. But there are plenty of adults who develop type 1 diabetes, and an increasing number of children and adolescents are getting type 2 diabetes. In the same way, type 1 diabetes is sometimes referred to as insulin-dependent diabetes mellitus (IDDM), and type 2 as non-insulin-dependent diabetes mellitus (NIDDM). This is also misleading, because many people with type 2 diabetes require insulin for adequate blood sugar control.

Insulin is a hormone that is responsible for ushering blood glucose (sugar) into cells; if not enough gets into cells, high blood glucose results. As we describe in The Best Life Guide to Managing Diabetes and Pre-Diabetes, there are two main problems with insulin in diabetes: either the body is not making enough insulin, or it is not responding properly to the insulin that is being made, or both.

In simple terms, type 1 diabetes means the body is not making any insulin. The vast majority of people with type 1 have an autoimmune problem causing their diabetes. This means that the body’s immune system-which should be protecting us against invading viruses and bacteria-instead attacks and destroys the insulin-producing cells in the pancreas. Because insulin is necessary for survival, and because people with type 1 diabetes make no insulin, they must take insulin.

Type 2 diabetes is much more common, but is also a little more complicated. People with type 2 diabetes start out making plenty of insulin, but their bodies do not respond to it properly. This is termed insulin resistance, and it is mostly caused by abdominal obesity. Type 2 diabetes tends to occur in adults. Unfortunately, as children and adolescents become more overweight or obese, more of them are developing insulin resistance, and some are even developing type 2 diabetes. In addition, the amount of insulin made by people with type 2 diabetes tends to decline with time. Over time, many people with type 2 diabetes do not make enough insulin for oral medications to work. These individuals need to be treated with insulin, so it is misleading to call type 2 diabetes “non-insulin dependent.”

Continue Learning about Diabetes


Diabetes mellitus (MEL-ih-tus), often referred to as diabetes, is characterized by high blood glucose (sugar) levels that result from the body’s inability to produce enough insulin and/or effectively utilize the insulin. Diabetes ...

is a serious, life-long condition and the sixth leading cause of death in the United States. Diabetes is a disorder of metabolism (the body's way of digesting food and converting it into energy). There are three forms of diabetes. Type 1 diabetes is an autoimmune disease that accounts for five- to 10-percent of all diagnosed cases of diabetes. Type 2 diabetes may account for 90- to 95-percent of all diagnosed cases. The third type of diabetes occurs in pregnancy and is referred to as gestational diabetes. Left untreated, gestational diabetes can cause health issues for pregnant women and their babies. People with diabetes can take preventive steps to control this disease and decrease the risk of further complications.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.