What is diabetes mellitus?

Diabetes mellitus is a disease that prevents your body from properly using the energy from the food you eat. Diabetes occurs in one of the following situations:

  • The pancreas (an organ behind your stomach) produces little insulin or no insulin at all. Insulin is a naturally occurring hormone, produced by the beta cells of the pancreas, which helps the body use sugar for energy.

-Or-

  • The pancreas makes insulin, but the insulin made doesn't work as it should. This condition is called insulin resistance.

To better understand diabetes, it helps to know more about how the body uses food for energy (a process called metabolism).

Your body is made up of millions of cells. To make energy, the cells need food in a very simple form. When you eat or drink, much of your food is broken down into a simple sugar called glucose. Glucose provides the energy your body needs for daily activities.

The blood vessels and blood are the highways that transport sugar from where it is either taken in (the stomach) or manufactured (in the liver) to the cells where it is used (muscles) or where it is stored (fat). Sugar isn't able to go into the cells by itself. The pancreas releases insulin into the blood, which serves as the helper, or the "key," that lets sugar into the cells for use as energy.

When sugar leaves the bloodstream and enters the cells, the blood sugar level is lowered. Without insulin, or the "key," sugar can't get into the body's cells for use as energy. This causes sugar to rise. Too much sugar in the blood is called "hyperglycemia" (high blood sugar).

What are the types of diabetes?

There are two main types of diabetes: Type 1 and Type 2:

  • Type 1 diabetes occurs because the insulin-producing cells of the pancreas (beta cells) are damaged. In Type 1 diabetes, the pancreas makes little or no insulin, so sugar can;t get into the body's cells for use as energy. People with Type 1 diabetes must use insulin injections to control their blood glucose. Type 1 is the most common form of diabetes in people who are under age 30, but it can occur at any age. Ten percent of people with diabetes are diagnosed with Type 1.
  • In Type 2 diabetes (adult onset diabetes), the pancreas makes insulin, but it either doesn't produce enough, or the insulin doesn't work properly. Nine out of 10 people with diabetes have Type 2. This type occurs most often in people who are over 40 years old but can occur even in childhood if there are risk factors present. Type 2 diabetes may sometimes be controlled with a combination of diet, weight management and exercise. However, treatment also may include oral glucose-lowering medications (taken by mouth) or insulin injections (shots).

Other types of diabetes might result from pregnancy (gestational diabetes), surgery, use of certain medicines, various illnesses and other specific causes.

What is gestational diabetes?

Gestational diabetes occurs when there is a high blood glucose level during pregnancy. As pregnancy progresses, the developing baby has a greater need for glucose. Hormone changes during pregnancy also affect the action of insulin, which brings about high blood glucose levels.

Pregnant women who have a greater risk of developing gestational diabetes include those who:

Blood glucose levels usually return to normal after childbirth. However, women who have had gestational diabetes have an increased risk of developing Type 2 diabetes later in life.

What causes diabetes?

The causes of diabetes are not known. The following risk factors may increase your chance of getting diabetes:

  • Family history of diabetes or a personal history of gestational diabetes.
  • African-American, Hispanic, Native American, or Asian-American race, Pacific Islander or ethnic background.
  • Injury to the pancreas (such as infection, tumor, surgery or accident).
  • Autoimmune disease.
  • Age (risk increases with age).
  • Physical stress (such as surgery or illness).

There are risk factors that you might have more control over, including:

  • High blood pressure.
  • Abnormal blood cholesterol or triglyceride levels.
  • Smoking.
  • Being overweight.
  • Use of certain medications, including steroids

It is important to note that sugar itself doesn't cause diabetes. Eating a lot of sugar can lead to tooth decay, but it doesn't cause diabetes.

What are the symptoms of diabetes?

The symptoms of diabetes include:

  • Increased thirst.
  • Increased hunger (especially after eating).
  • Dry mouth.
  • Frequent urination.
  • Unexplained weight loss (even though you are eating and feel hungry).

Other symptoms include:

What are the symptoms of low blood sugar?

Most people have symptoms of low blood sugar (hypoglycemia) when their blood sugar is less than 70 mg/dl. (Your healthcare provider will tell you how to test your blood sugar level.)

When your blood sugar is low, your body gives out signs that you need food. Different people have different symptoms. You will learn to know your symptoms.

Common early symptoms of low blood sugar include the following:

  • Feeling weak or dizzy, including trembling and feeling shaky.
  • Feeling hungry.
  • Sweating.
  • Pounding heart.
  • Pale skin.
  • Feeling frightened or anxious.

Late symptoms of low blood sugar include:

  • Feeling confused or being able to keep your mind on one subject.
  • Headache.
  • Poor coordination.
  • Bad dreams or nightmares.
  • Feeling cranky.
  • Numbness in your mouth and tongue.
  • Passing out.

Last reviewed by a Cleveland Clinic medical professional on 10/02/2018.

References

  • American Diabetes Association. Diabetes Basics. Accessed 6/8/2020.
  • The National Institute of Diabetes and Digestive and Kidney Diseases. What is Diabetes? Accessed 6/08/20.
  • American Diabetes Association. A1C and eAG. Accessed 6/8/2020.

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