Impaired Fasting Glucose (IFG), Impaired Glucose Tolerance (IGT), and an A1C of 5.7-6.4% are included in a category of increased risk for future diabetes (also known as pre-diabetes). This is defined as blood glucose or A1C levels higher than normal but not high enough to be characterized as diabetes. People with IFG, IGT, and an increase A1C are at risk for developing type 2 diabetes and also have an increase risk of heart disease and stroke. With modest weight loss and moderate physical activity, people with pre-diabetes can delay or prevent type 2 diabetes.
New recommendations by American Diabetes Association (ADA)
define A1C testing as an appropriate test for diagnosing diabetes when A1C is greater than or equal to 6.5%. Diagnosis should be confirmed by a repeat A1C test unless clinical symptoms and glucose levels over 200 mg/dL are present.
A1C testing may not be reliable due to patient factors which preclude its interpretation (e.g. any anemia, hemoglobinopathy or abnormal erythrocyte turnover). In this case previously recommended diagnostic measures should be used (fasting plasma glucose and 2 hour oral glucose tolerance test).