Type 2 diabetes accounts for about 90% of all diagnosed cases of diabetes. The reality is that most cases are not diagnosed, 20 million Americans have a condition, either impaired fasting glucose and impaired glucose tolerance, that puts them at higher risk for the disease. And, experts estimate that 5 million Americans have type 2 diabetes but haven't been diagnosed yet.

Type 2 diabetes is usually diagnosed in adults over age 40 but can develop in younger people as well. People with a family history of type 2 diabetes have a greater risk of developing it. In addition, type 2 diabetes very commonly occurs in overweight people and those who are physically inactive.

Other risk factors include: history of having gestational diabetes (diabetes during pregnancy), polycystic ovary syndrome and history of high blood pressure, high cholesterol levels and history of impaired glucose tolerance or impaired fasting glucose. People with metabolic syndrome (a combination of high cholesterol, high blood pressure, abdominal obesity and abnormal ability to process glucose are also at higher risk for the disease.