An A1C chart shows how A1C levels correspond to average blood sugar levels, explains Mayo Clinic. For example, a person whose A1C level is 7 percent has an estimated average blood sugar level of 154 milligrams per deciliter. A person whose A1C level ranges from 4.5 to 6 percent is in the normal range. One whose A1C ranges from 5.7 to 6.4 percent is prediabetic.
A1C charts can be organized in various ways, with A1C level and average blood glucose displayed in two columns or displayed in two rows, and some charts contain additional information, such as the levels of risk associated with given A1C level ranges, note the Latino Diabetes Association and DiabetesChart. If the chart is organized in columns, simply find the A1C level and move horizontally to the average blood glucose level column to locate the corresponding value for average blood glucose. If the chart is organized in rows, find the A1C level and move vertically either upward or downward to the corresponding value in the average blood glucose level column.
The hemoglobin A1C test is useful because, unlike daily home testing, the A1C test shows the average blood glucose level over the past two to three months, according to WebMD. This can help doctors decide whether to adjust dosages of their patients' diabetes medications. Uncontrolled diabetes allows sugar to accumulate in the blood where it combines with hemoglobin. Measuring this effect is the basis of the hemoglobin A1C test, which is also known as the glycated hemoglobin test or the glycohemoglobin test. A1C levels that exceed 6.5 percent on two separate tests indicate diabetes.