A glycated hemoglobin test result between 5.7 and 6.4 percent indicates prediabetes. Doctors use a variety of tests to determine whether patients are prediabetic, according to Mayo Clinic. A result of 6.5 or more on two tests indicates diabetes. Doctors also measure fasting blood sugar and glucose tolerance.
Fasting blood sugar levels between 100 and 125 milligrams per deciliter indicate the patient is prediabetic, explains Mayo Clinic. Health providers use oral glucose tolerate tests to diagnose diabetes in pregnant women. In a glucose tolerance test, a blood sugar level from 140 to 199 milligrams per deciliter is prediabetic.
Prediabetes can begin to cause damage to the heart and circulatory system, notes Mayo Clinic. Prediabetics are more likely to become Type 2 diabetics within the span of 10 years after the initial diagnosis.