How often should you have your HbA1c measured?

How often you should have your HbA1c measured depends on your situation. If you do not yet have diabetes or prediabetes, there is no fixed guideline for repeat testing, but a one-off measurement is worthwhile if you have risk factors. Worldwide, roughly 1 in 3 adults has prediabetes, and many are unaware of it.

If you have prediabetes (HbA1c between 5.7% and 6.4%), annual monitoring is sensible. Every year, approximately 10% of people with prediabetes go on to develop type 2 diabetes. Measuring regularly gives you the opportunity to course-correct in time through lifestyle changes.

With type 2 diabetes, the rule is: measuring only makes sense if you actually do something with the results. A meta-analysis of 22 studies shows that self-monitoring of blood glucose lowers HbA1c by an average of 0.30 percentage points. That effect is strongest at 8 to 11 measurements per week, combined with lifestyle changes. A Portuguese study of 117 patients found no relationship between measurement frequency and HbA1c outcome, however, suggesting that you also need to take real action based on the numbers.

If you use a continuous glucose monitor (a small device that tracks your glucose levels throughout the day), the duration of use matters. People who wore such a monitor for more than 270 days per year saw their HbA1c fall by an average of 1.52 percentage points over one year. In people who wore it for fewer than 270 days, the improvement stopped after just six months. This was an observational study, so causality has not been definitively proven.

How often you have your HbA1c checked via a blood draw at the doctor is a separate matter from daily self-monitoring. For people with well-controlled diabetes, twice a year is common; with poorer control or medication changes, more frequent checks are appropriate. Discuss with your doctor which frequency suits your situation.