It is unclear how long one must wait to get his prediabetes numbers back, but if he is diagnosed with prediabetes, he must get retested every one to two years, according to the American Diabetes Association.
A person with prediabetes has higher-than-normal blood glucose levels but not high enough to be considered diabetes. Prediabetes is referred to as impaired glucose tolerance or impaired fasting glucose. Since prediabetes is asymptomatic, a person learns whether he has the condition only when he is tested for diabetes. Doctors use one of three blood tests to test for diabetes: fasting plasma glucose test, oral glucose tolerance test and hemoglobin A1C, according to WebMd.