What is a healthy HbA1c level?
Below 6.5% is the widely used cut-off for normal blood sugar regulation, but that cut-off misses many people with undetected diabetes. Discuss your result with your doctor, because what counts as "healthy" depends on your situation.
HbA1c measures how much sugar has attached to your red blood cells over the past two to three months. The result is expressed as a percentage. A value below 6.5% is the widely used cut-off below which someone is considered not to have diabetes. Above that cut-off, a diagnosis of diabetes is made.
That 6.5% cut-off is sharp at the top end: if someone is above it, the diagnosis is almost always correct. But it also misses a lot of people. Roughly half of people with undetected diabetes have a value below 6.5% and are therefore not identified during screening. Researchers have therefore looked at a lower cut-off of 6.03%. That catches more people, but also more often produces a result that turns out to be a false positive.
If you already have type 2 diabetes, below 7% is the standard treatment target. That sounds like a small margin, but fewer than half of people with type 2 diabetes reach that target with tablets, depending on the medicine used. People who start treatment with a higher HbA1c have a smaller chance of getting below 7%.
HbA1c is the most accurate blood sugar test we have, better than alternatives such as glycated albumin. However, in conditions that shorten the lifespan of red blood cells, such as anaemia, the result can be less reliable. Always discuss your result with your doctor, because the right cut-off depends on your age, your health, and whether you are already receiving treatment.
This answer draws on a large screening study that examined the diagnostic accuracy of HbA1c in the general population, a study in more than a hundred adults that compared HbA1c with an alternative measurement, and an analysis of people with type 2 diabetes who were treated with non-insulin medication. The diagnostic cut-off values are well supported; the treatment target of below 7% is widely adopted in guidelines but rests here on research that measures association, not cause and effect.
How often should you have your HbA1c measured?
In stable diabetes, measuring twice a year is standard; when values fluctuate or treatment has changed, four times a year is the norm. Discuss the frequency that suits you best with your doctor.
How do you lower a high HbA1c?
Several medications demonstrably lower HbA1c: the weekly semaglutide injection has the strongest evidence base, but oral combinations involving empagliflozin or semaglutide also offer good evidence. Discuss with your doctor which option suits your situation, side-effect profile and reimbursement coverage.
Can your HbA1c also be too low?
An HbA1c below 5.0% is associated with an increased risk of death in people without diabetes, although this is likely a signal of an underlying condition. Always have a strikingly low value investigated by your doctor.
What does your HbA1c tell you about your risk of diabetes and ageing?
An elevated HbA1c, even well below the official diabetes threshold, is associated with a greater risk of diabetes, kidney damage, eye complications and possibly dementia. Have your HbA1c checked regularly and discuss with your doctor what a healthy target value is for you.
How do I know if my blood sugar is healthy (prediabetes)?
Prediabetes can be diagnosed with a blood test at your GP's practice, preferably using the glucose tolerance test. A raised value is a signal to act on your lifestyle promptly: exercise and eating fewer calories are the most effective approach.
What does stable blood sugar do for healthy ageing?
A stable, low blood sugar is associated worldwide with more healthy life years. The association is clear, but the exact gain per individual cannot be quantified on the basis of this research.