What is Type 2 Diabetes and Pre-diabetes?
Explanation of type 2 diabetes and it's precursor, pre-diabetes, where blood sugar levels are not high enough for a diagnosis of diabetes.
Type 2 diabetes is a disorder that affects the way the body uses digested food for growth and energy. Normally, the food one eats is broken down into glucose, a form of sugar. The glucose then passes into the bloodstream, where it is used by the cells for growth and energy. For glucose to reach the cells, however, insulin must be present. Insulin is a hormone produced by the pancreas, a fist-sized gland behind the stomach.
Most people with type 2 diabetes have two problems: insulin resistance—a condition in which muscle, liver, and fat cells do not use insulin properly—and reduced insulin production by the pancreas. As a result, glucose builds up in the blood, overflows into the urine, and passes out of the body, never fulfilling its role as the body's main source of fuel.
About 23.6 million people in the United States have diabetes. Of those, 17.9 million are diagnosed and 5.7 million are undiagnosed. Ninety to 95 percent of people with diabetes have type 2 diabetes. Diabetes is the main cause of kidney failure, limb amputation, and new-onset blindness in American adults. People with diabetes are more likely than people without diabetes to develop and die from diseases of the heart and blood vessels, called cardiovascular disease. Adults with diabetes have heart disease death rates about two to four times higher than adults without diabetes, and the risk for stroke is two to four times higher among people with diabetes.
Pre-diabetes: A Higher Risk for Diabetes
Pre-diabetes is a condition in which blood glucose levels are higher than normal but not high enough for a diagnosis of diabetes. Pre-diabetes is also called impaired glucose tolerance (IGT) or impaired fasting glucose (IFG), depending on the test used to measure blood glucose levels. Having pre-diabetes puts one at higher risk for developing type 2 diabetes. People with pre-diabetes are also at increased risk for developing cardiovascular disease.
Pre-diabetes is becoming more common in the United States. The U.S. Department of Health and Human Services estimates that about one in four U.S. adults aged 20 years or older—or 57 million people—had pre-diabetes in 2007. Those with pre-diabetes are likely to develop type 2 diabetes within 10 years, unless they take steps to prevent or delay diabetes.
The American Diabetes Association recommends that testing to detect pre-diabetes and type 2 diabetes be considered in adults without symptoms who are overweight or obese and have one or more additional risk factors for diabetes. In those without these risk factors, testing should begin at age 45.
Risk factors for pre-diabetes and diabetes—in addition to being overweight or obese or being age 45 or older—include the following:
- being physically inactive
- having a parent, brother, or sister with diabetes
- having a family background that is African American, Alaska Native, American Indian, Asian American, Hispanic/Latino, or Pacific Islander
- giving birth to a baby weighing more than 9 pounds or being diagnosed with gestational diabetes—diabetes first found during pregnancy
- having high blood pressure—140/90 mmHg or above—or being treated for high blood pressure
- having HDL, or "good," cholesterol below 35 mg/dL, or a triglyceride level above 250 mg/dL
- having polycystic ovary syndrome, also called PCOS
- having impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) on previous testing
- having other conditions associated with insulin resistance, such as severe obesity or a condition called acanthosis nigricans, characterized by a dark, velvety rash around the neck or armpits
- having a history of cardiovascular disease
If results of testing are normal, testing should be repeated at least every 3 years. Doctors may recommend more frequent testing depending on initial results and risk status.
Last Updated: 10 March 2016
Reviewed by Harry Croft, MD