Diabetes is a health condition that affects an estimated 23.6 million people in the United States. In people who have diabetes, abnormal levels of the hormone insulin cause glucose (sugar) to build up in the blood. If left untreated or treated improperly, these high blood glucose levels can lead to coma or even death.

What Causes Diabetes?

Researchers are not sure exactly what causes diabetes, but it is thought to result from a combination of genetics and environmental factors.

If you have diabetes, your body has problems producing or utilizing insulin. Insulin is a hormone that is produced by your pancreas. Your body breaks down the food you eat into a form of sugar known as glucose. Insulin is required to convert this glucose into the energy your body needs to grow and perform the activities of daily life.

Diabetes is diagnosed with a simple blood test that measures the level of glucose in your blood, either while you are fasting (using the fasting plasma glucose test, or FPG) or two hours after drinking a sugary drink (using the oral glucose tolerance test, or OGTT). You have diabetes if your FPG results are 126 milligrams per deciliter (mg/dL) or higher, or your OGTT results are 200 mg/dL or higher.

Understanding Type 1 Diabetes

In type 1 diabetes, which is an autoimmune disease, your immune system mistakenly attacks beta cells, cells in your pancreas that produce insulin. This causes your pancreas to produce little or no insulin, leading to a build-up of glucose in your blood.

It is estimated that 5 to 10 percent of Americans with diabetes have type 1 diabetes. Symptoms of type 1 diabetes usually develop rather suddenly during childhood or young adulthood, and may include:

  • Thirst
  • Increased urination
  • Persistent hunger
  • Unexplained weight loss
  • Blurry vision
  • Fatigue

People who have type 1 diabetes must carefully manage their disease through diet, exercise, and injectable insulin.

Understanding Type 2 Diabetes

Type 2 diabetes accounts for 90 to 95 percent of all diabetes cases. In type 2 diabetes, the body uses insulin ineffectively, which is called insulin resistance. Over time, insulin resistance causes a decrease in insulin production, which leads to a build-up of glucose in the blood.

Type 2 diabetes tends to develop in older people, people who are obese, and those who do not exercise. The symptoms of type 2 diabetes are similar to those of type 1 diabetes, but they usually occur more gradually. Symptoms may include:

  • Fatigue
  • Frequent urination
  • Thirst
  • Hunger
  • Weight loss
  • Blurry vision
  • Problems with wound healing
  • Frequent yeast infections

Many people are able to manage — or even cure — their type 2 diabetes with diet and exercise. Some people, however, need to take insulin or other medications to get their blood glucose levels under control.

Understanding Gestational Diabetes

Gestational diabetes occurs in about 3 to 8 percent of pregnant women, usually during late pregnancy. Researchers believe that gestational diabetes is the result of hormonal changes during pregnancy or a pregnancy-associated insulin deficiency.

If left uncontrolled, gestational diabetes can lead to problems in the baby, including high birth weight and breathing problems at birth. And while gestational diabetes often disappears after the baby's birth, women who have had gestational diabetes have a 40 to 60 percent chance of later developing type 2 diabetes. Exercising and maintaining a healthy weight can reduce your risk of developing gestational diabetes. Treatments for gestational diabetes may include changes in diet, exercise, and sometimes insulin injections.

Diabetes in any form is a serious condition that requires close monitoring by your health care team. If you take steps to keep your diabetes under control, you can increase your chances of living a full and healthy life.