If there’s one number all patients with diabetes should know, it’s their hemoglobin A1c (HbA1c or A1C) level: a measure of their overall blood glucose control for the past 3 months. Blood glucose levels fluctuate from hour to hour, day to day; but the A1C level reflects the overall average and is the best test to monitor blood glucose control in the past 3 months.
The A1C test is an important tool for diagnosing and monitoring diabetes. After diagnosis, most patients should take the A1C test every 3 months, though the test might be spaced to every 6 months for patients with consistently good levels.
Optimal A1C levels to reduce the risk of developing complications in most non-pregnant persons with diabetes are less than 7%, though older persons with multiple medications and limited mobility may have less stringent goals at less than 8%. Levels higher than 9% usually reveal overall poor blood glucose control.
The following table illustrates how A1C levels relate to average blood glucose, which is given in mmol/L (outside the United States) and mg/dl (within the United States). For example, an A1C level of 7% reflects an estimated average blood glucose level of 154 mg/dl.
A1C level and estimated average blood glucose levels.
|A1C (%)||Blood Glucose (mg/dl)||Blood Glucose (mmol/L)|
Source: Adapted from Nathan DM, Kuenen J, Borg R, et al. Translating the A1C assay into estimated average glucose values. Diabetes Care, 2008; Vol. 31(8) pp. 1473-8.
Point-of-care A1C Machines
Until just a few years ago, A1C levels could only be measured in a laboratory. However, now special machines have been approved to measure A1C with just a fingerstick in an office, and in less than 10 minutes.
What you need to know:
- Different machines (even machines from the same brand) may give different A1C levels. Ask your provider for a laboratory measurement of your A1C to compare with the results from the point-of-care machine, especially if the results are surprising. That way, you’ll know roughly how much the results differ.
- Ask your healthcare provider about your A1C target.
- Point-of-care A1C machines can be used to obtain same day A1C results in the clinic or, sometimes, at home for people with diabetes. However, they are not a replacement for self-monitoring of blood glucose levels at home using a glucose meter.
- People with diabetes may have more productive and informed conversations with their healthcare providers by having their point-of-care A1C levels checked during a routine clinic visit, if they have not had an A1C test performed in the last 3 months. This can motivate people to better manage their blood glucose!