Diagnosis A1C Test Whenever blood glucose become elevated above normal, some of the hemoglobin protein in your red blood cells will be coated with sugar (glycosylated). The A1C blood test measures the percentage of hemoglobin that has become glycosylated. This allows an indirect measurement of the blood glucose levels over the previous 2-3 months versus the snapshot image provided by blood glucose tests. For this reason, the A1C has become the screening method of choice for diabetes detection and long-term monitoring.
It is recommended that insulin dependent diabetics, both Type 1 and Type 2 receive A1C blood tests 3-4 time/year. Well controlled Type 2 diabetics who don’t need insulin should be checked twice a year. Abnormal A1C results should be check again because artificially high and low results can occur in response to illness and some existing medical conditions.
A result greater that 6.5% indicates diabetes. A result between 5.7 and 6.4% indicates pre-diabetes. A result greater than 8% means that the diabetes is poorly control and the patient is in danger of developing serious complications. Well controlled diabetes will have A1C results less than 7%. Fasting Plasma Glucose (FPG) After a patient has not eaten or drunk anything other that water for 8 hours, blood is drawn to determine glucose levels. A fasting blood glucose level at 126 mg/dl indicates diabetes. A fasting blood glucose of 100 - 125 mg/dl indicates prediabetes. Oral Glucose Tolerance Test (OGTT) For the OGTT, a initial blood glucose is measured and then the patient drinks a special high glucose drink. After two hours, the blood glucose level is again measured to determine how well the body processed the glucose. Diabetic patients will have blood glucose at 200 mg/dl or higher. Prediabetics will have a blood glucose of 100 - 125 mg/dl Random Plasma Glucose Test. Blood glucose can also be measured if the patient has concerning symptoms. Diabetes is diagnosed if the blood glucose level is 200 mg/dl or higher.