Diabetes mellitus is a disease characterized by high levels of sugar in the blood. People with diabetes have problems converting the food they eat into usable energy. There are two types of diabetes mellitus: type 1 (type I) and type 2 (type II).

What is type 2 diabetes?

Type 2 diabetes, formerly called noninsulin-dependent diabetes, is a condition in which the body does not make enough, or cannot properly use, the pancreatic hormone insulin. Insulin tells the body’s cells to absorb the sugar known as glucose from the blood and to use it as fuel. If the body makes only low levels of insulin or if cells become resistant to its effects, glucose will remain in the bloodstream causing chronically high blood sugar levels and preventing cells from taking up the sugar they need for metabolism. Type 2 diabetes accounts for between 90 and 95 percent of all diabetes cases in the United States.

Type I diabetes, formerly called insulin-dependent diabetes, is a much less common disorder in which the pancreas makes no insulin at all. As in type 2 diabetes, this results in high blood sugar levels and difficulty obtaining energy from food.

The American Diabetes Association (ADA) estimates that 20.8 million Americans, or about 7% of the population, have diabetes and about 95% of these cases are type 2. 14.6 million of these people have actually been diagnosed with the disease, but an estimated 6.2 million people have type 2 diabetes and do not know it. The ADA also estimates that 54 million people have prediabetes, a condition in which their blood sugar is elevated but not high enough to be considered diabetes.