About Diabetes – American Heart Association

"Diabetes mellitus," more commonly referred to as "diabetes," is a condition that causes blood sugar to rise to dangerous levels: a fasting blood glucose of 126 milligrams per deciliter (mg/dL) or more.

How Diabetes Develops

Types of Diabetes

Type 1DiabetesType 1 diabetes is a serious condition that occurs when the pancreas makes little or no insulin. Without insulin, the body is unable to take the glucose (blood sugar) it gets from food into cells to fuel the body. So without daily injections of insulin, people with type 1 diabetes won't survive. For that reason, this type of diabetes is also referred to as insulin-dependent diabetes.

Type 1 diabetes was previously known as juvenile diabetes because it's usually diagnosed in children and young adults. However, this chronic, lifelong disease can strike at any age, and those with a family history of it are particularly at risk.

Health Risks for Type 1 Diabetes

During the development of type 1 diabetes, the body's immune system attacks certain cells (called beta cells) in the pancreas. Although the reasons this occurs are still unknown, the effects are clear. Once these cells are destroyed, the pancreas produces little or no insulin, so the glucose stays in the blood. When there's too much glucose in the blood, especially for prolonged periods, all the organ systems in the body suffer long-term damage. Learn more about the health consequences of diabetes and how to treat it.

Type2DiabetesType 2 diabetes is the most common form of diabetes. Historically, type 2 diabetes has been diagnosed primarily in middle-aged adults. Today, however, adolescents and young adults are developing type 2 diabetes at an alarming rate. This correlates with the increasing incidence of obesity and physical inactivity in this population, both of which are risk factors for type 2 diabetes.

This type of diabetes can occur when:

Precursors to Diabetes

Pre-diabetesPre-diabetes means your body is not fully able to handle the job of converting sugars into energy. If youve been told by your healthcare provider that you have pre-diabetes it also means that without making some healthy changes, your body will most likely eventually develop diabetes. Learn more about pre-diabetes. Insulin Resistance Both type 2 diabetes and pre-diabetes usually result from insulin resistance.

Insulin resistance, which is a condition that affects more than 60 million Americans, occurs when the body can't use insulin efficiently. To compensate, the pancreas releases more and more insulin to try to keep blood sugar levels normal. Gradually, the insulin-producing cells in the pancreas become defective and ultimately decrease in total number. As a result, blood sugar levels begin to rise, causing pre-diabetes and, eventually, type 2 diabetes to develop.

When a fasting individual has too much glucose in the blood (hyperglycemia) or too much insulin in the blood (hyperinsulinemia), it indicates a person may have insulin resistance.

Health Risks of Insulin Resistance

People with insulin resistance are at greater risk of developing type 2 diabetes. They also are more likely to have too much LDL ("bad") cholesterol, not enough HDL ("good") cholesterol, and high triglycerides, which cause atherosclerosis.

Untreated diabetes can lead to many serious medical problems, including heart disease and stroke. That's why it's important to be aware of the symptoms as well as the risk factors and to take appropriate steps to prevent and treat insulin resistance and diabetes.

This content was last reviewed on 6/28/2012.

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About Diabetes - American Heart Association