The National Institutes of Health states that a person has prediabetes if they have a fasting blood glucose level between 100-125 mg/dL or a two-hour blood glucose level between 140-199 mg/dL after an oral glucose tolerance test.
According to the Mayo Clinic, people with prediabetes will develop type 2 diabetes within 10 years or less if preventative lifestyle changes aren't made. Doctors state that diabetes can be avoided and prediabetes can be reversed with positive lifestyle changes, such as increased exercise, a healthful diet and maintaining a healthy weight.
The American Diabetes Association finds that, often, there are no clear signs of prediabetes, and it is most often diagnosed when a person is being tested for diabetes. It is recommended that a person with prediabetes be tested for type 2 diabetes every two years.