Almost every person who has diabetes knows that the HbA1c (hemoglobin A1c) test is one of the best tools available for tracking diabetes patients’ overall blood sugar level for any 90 days. For example, a patient may register a blood glucose level of 8.2 mg/dL at the start of January but then undertakes a serious exercise and meals routine that leads to an A1c reading in April of 7.1 mg/dL.