"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.
After eating a meal, the food is broken down by the digestive system and blood sugar (or glucose) rises. The pancreas is an organ near the stomach, which produces a hormone called insulin. With the help of insulin, the body's cells take up the glucose and use it for energy. When your body does not produce enough insulin and/or does not efficiently use the insulin it produces, sugar levels rise in the bloodstream. When this happens, it can cause two problems:
How Diabetes Develops
- Right away, the body's cells may be starved for energy.
- Over time, high blood glucose levels may damage the eyes, kidneys, nerves or heart.
Types of DiabetesThere are two main types of diabetes: type 1 diabetes and type 2 diabetes. A family history of diabetes can significantly increase a person's risk of developing the condition.
Type 1 Diabetes
Type 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. People with type 1 diabetes must take daily insulin or other medications daily. 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 type 1 diabetes have a greater 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.
Type 2 Diabetes
Type 2 diabetes is the most common form of diabetes. Historically, type 2 diabetes has been diagnosed primarily in 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:
- The body develops "insulin resistance" and can't make efficient use of the insulin it makes, and
- The pancreas gradually loses its capacity to produce insulin.
Precursors to DiabetesIn addition to full-blown diabetes mellitus, there are precursors to the disease:
Insulin resistance is a condition that affects more than 60 million Americans. Insulin resistance occurs when the body makes insulin but does not use it efficiently and glucose builds up in the blood instead of being used by cells. To compensate for the high blood sugar levels, the insulin-producing cells in the pancreas release more and more insulin to try to keep blood sugar levels normal. Gradually, these cells fail to keep up with the body's need for insulin and blood sugar levels begin to rise. Insulin resistance can lead to both pre-diabetes and type 2 diabetes.
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.
Pre-diabetes means that your blood sugar levels are higher than normal, but not to the levels to be diagnosed with diabetes. If you’ve been told by your healthcare provider that you have “pre-diabetes” it also means that without making some healthy changes, you have a higher risk of developing type 2 diabetes. Learn more about pre-diabetes.
Health Risks of Insulin Resistance
People with insulin resistance are at greater risk of developing type 2 diabetes and cardiovascular disease. They also are more likely to have a history of being obese and physically inactive and to have other cardiovascular risk factors such as dyslipidemia (too much) LDL ("bad") cholesterol, not enough HDL ("good") cholesterol, or high triglycerides, hypertension, and other factors that can increase cardiovascular risk.
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 August 2015.