Understanding Diabetes -- the Basics

Diabetes, the most common disorder of the endocrine (hormone) system, occurs when blood sugar levels in the body consistently stay above normal. It affects more than 30 million people in the U.S. alone.

Diabetes is a disease brought on by either the body's inability to make insulin (type 1 diabetes) or by the body not responding to the effects of insulin (type 2 diabetes). It can also appear during pregnancy. Insulin is one of the main hormones that regulates blood sugar levels and allows the body to use sugar (called glucose) for energy. Talk with your doctor about the different types of diabetes and your risk for this disease.


In the U.S., 84.1 million adults have blood sugar levels that are higher than normal, but not high enough to be classified as diabetes. This is known as prediabetes, or impaired glucose tolerance. While people with prediabetes usually have no symptoms, it’s almost always present before a person develops type 2 diabetes. However, complications normally associated with diabetes, such as heart disease, can begin to develop even when a person has only pre-diabetes.

Once type 2 diabetes develops, symptoms include unusual thirst, a frequent need to urinate, blurred vision, or extreme fatigue -- or there may be no symptoms. Talk to your doctor to see if you need to be tested for prediabetes. By identifying the signs of prediabetes before diabetes occurs, you may be able to prevent type 2 diabetes and lower your risk of complications associated with this condition, such as heart disease.


Type 1 Diabetes

Type 1 diabetes occurs because the insulin-producing cells of the pancreas (called beta cells) are destroyed by the immune system. People with type 1 diabetes produce no insulin and must use insulin injections to control their blood sugar.

Type 1 diabetes most commonly starts in people under age 20, but may occur at any age.

For more detail, see WebMD's article Type 1 Diabetes.

Type 2 Diabetes

With type 2 diabetes, the body continues to produce insulin, although insulin production by the body may significantly decrease over time. The pancreas produces either not enough insulin, or the body is unable to recognize insulin and use it properly. When there isn't enough insulin or the insulin is not used as it should be, glucose can't get into the body's cells to be used as energy. This glucose then builds up in the blood.


Approximately 30.3 million people in the U.S. have diabetes, and the great majority of them have type 2 diabetes. While most of these cases can be prevented, it remains for adults the leading cause of diabetes-related complications such as blindness, non-traumatic amputations, and chronic kidney failure. Type 2 diabetes usually occurs in people over age 40 who are overweight, but it can occur in people who are not overweight. In the past, it was referred to as "adult-onset diabetes," but now it has started to appear more often in children because of the rise in obesity in young people.

Some people can manage their type 2 diabetes by controlling their weight, watching their diet, and exercising regularly. Others may also need to take a diabetes pill that helps their body use insulin better, and/or take insulin injections.

Often, doctors are able to detect the likelihood of type 2 diabetes before the condition actually occurs. Commonly referred to as prediabetes, this condition occurs when a person's blood sugar levels are higher than normal, but not high enough for a diagnosis of type 2 diabetes.

For more detail, see WebMD's article Type 2 Diabetes.


Gestational Diabetes

Hormone changes during pregnancy can affect insulin's ability to work properly. The condition, called gestational diabetes, occurs in about 6% to 9%of all pregnancies.

Pregnant women who have an increased risk of developing gestational diabetes are those who are over age 25, are above their normal body weight before pregnancy, have a family history of diabetes, or are Hispanic, black, Native American, or Asian.

Screening for gestational diabetes is performed during pregnancy. Left untreated, gestational diabetes increases the risk of complications to both the mother and their unborn child.

Usually, blood sugar levels return to normal within six weeks of childbirth. However, women who have had gestational diabetes have an increased risk of developing type 2 diabetes later in life.

For more detail, see WebMD's article Gestational Diabetes.

What Are the Symptoms of Diabetes?

The symptoms of type 1 diabetes often occur suddenly and can be severe. They include:


The symptoms of type 2 diabetes may be the same as those listed above. Most often, there are no symptoms or a very gradual development of the above symptoms. Other symptoms may include:

With gestational diabetes, there are often no symptoms. If you do have symptoms, they might include:

  • Increased thirst
  • Increased urination
  • Increased hunger
  • Blurred vision

Pregnancy causes most women to have to urinate more often and to feel hungrier, so having these symptoms does not always mean that you have gestational diabetes. But it is important to get tested, because high blood sugar can cause problems for both you and your baby.

For more detail, see WebMD's article Type 2 Diabetes Symptoms.

How Is Diabetes Treated?

Diabetes can't be cured, but it can be treated and controlled. The goals of managing diabetes are to:

You hold the key to managing your diabetes. Work with your doctor to build a diabetes treatment plan that will guide you in:

  • Planning what you eat and following a balanced meal plan
  • Exercising regularly
  • Taking medicine, if prescribed, and closely following the guidelines on how and when to take it
  • Monitoring your blood glucose and blood pressure levels at home
  • Keeping your appointments with your health care providers
  • Getting lab tests when needed

Remember: What you do at home every day affects your blood sugar more than what your doctor can do every few months during your checkups.


For more detail, see WebMD's article Treating Type 2 Diabetes.



WebMD Medical Reference Reviewed by Nayana Ambardekar, MD on May 11, 2019



American Diabetes Association: “Recently Diagnosed.” 

National Diabetes Information Clearinghouse (NDIC): “Diabetes Overview.” 

National Diabetes Education Program: “About Diabetes and Pre-diabetes.” 

Saaddine, J. Annals of Internal Medicine, 2006.

CDC: "Diabetes During Pregnancy." "National Diabetes Statistics Report, 2017."


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