Why Is My HbA1c Still High Despite Eating Healthily?
In short
An HbA1c usually stays high despite healthy eating because of the amount and balance of carbohydrate, medication that needs reviewing, or sleep, stress and illness. Occasionally the test itself is affected. It does not mean you are doing something wrong.
Have you been trying to eat healthily, making better food choices and watching your portions, but your HbA1c is still higher than you expected? If you have Type 2 Diabetes, this can feel frustrating.
The good news is that an elevated HbA1c does not necessarily mean you are doing something wrong. Blood glucose is influenced by several factors, and understanding these can help you decide what to do next.
What does your HbA1c tell you?
HbA1c is a blood test that reflects your average blood glucose levels over approximately the previous 2 to 3 months.
For most adults, an HbA1c of 48 mmol/mol or above falls within the Diabetes diagnostic range. If you already have Diabetes, your personal HbA1c target may be different depending on your circumstances and treatment.
NICE suggests a target of 48 mmol/mol for many people, or 53 mmol/mol if you take a medicine that can cause hypos (NICE (opens in a new tab)). For the full ranges, see HbA1c levels explained.
Your result provides useful information, but it does not tell the whole story about your health or the effort you are putting into managing your Diabetes.
Why might your HbA1c remain high?
The most common reasons are the amount and balance of carbohydrate in your meals, medication that needs reviewing, and sleep, stress, illness or other medicines. Occasionally, a condition affects the test itself.
Can healthy foods still raise your HbA1c?
Yes. Foods such as wholegrain bread, rice, potatoes, fruit and oats can all form part of a balanced diet, but the amount and combination of carbohydrate-containing foods may still influence your blood glucose levels.
Rather than eliminating carbohydrates, it can be helpful to look at your usual portions, meal patterns and the balance of foods on your plate. My post on which foods help manage blood sugar explains why.
Could your Diabetes medication need reviewing?
It may. Type 2 Diabetes can change over time, and your treatment needs may change too. Even when you are making positive lifestyle changes, your current medication may not be enough to keep your blood glucose within your individual target range.
Speak to your Diabetes healthcare team about your results. Do not change your medication without medical advice.
Can sleep, stress or illness raise your HbA1c?
Yes. Poor sleep, stress, illness and some medications can affect blood glucose levels, and so can changes to your activity levels and daily routine.
Diabetes UK lists these among the things that can change an HbA1c result (Diabetes UK (opens in a new tab)):
- illness
- some medicines, such as steroids
- stress or depression
- changes to your lifestyle
Can the HbA1c test itself give a high result?
Occasionally. Conditions that affect red blood cells, such as haemolytic anaemia, sickle cell anaemia and thalassaemia, can make HbA1c results less accurate (Diabetes UK (opens in a new tab)).
Iron deficiency can also raise HbA1c without a matching rise in blood glucose, according to a 2015 University of Nottingham review (University of Nottingham (opens in a new tab)). If your HbA1c does not match your other blood sugar readings, mention it to your GP.
What can you do next if your HbA1c is still high?
Start by discussing your HbA1c result with your healthcare professional. You may also find it helpful to review your:
- meals
- activity levels
- sleep
- medication routine
Sometimes, the reason is not immediately obvious, which is why reviewing the bigger picture can be useful.
Can a Dietitian help bring your HbA1c down?
Yes. A registered Dietitian can help you explore your eating habits, identify realistic opportunities for change and develop a nutrition approach that suits your preferences and lifestyle.
If you have Type 2 Diabetes and feel unsure about what to change next, you do not have to work it all out alone. One-to-one dietetic consultations can help you understand your nutritional needs and develop practical strategies for managing your blood glucose and weight.
Interested in personalised support? See how I help with pre-Diabetes and Type 2 Diabetes, read what happens at a Dietitian appointment, or book a free discovery call.
Questions people ask about a high HbA1c
How long does it take to lower HbA1c?
Usually about 3 months before a blood test shows the difference. HbA1c reflects your average blood sugar over the previous 2 to 3 months, so the changes you make today show up at your next test, not straight away.
Can HbA1c be high if my blood sugar readings are normal?
It can. A finger-prick or fasting test shows your blood sugar at one moment, while HbA1c reflects the past 2 to 3 months, including the rises after meals. A condition that affects red blood cells can also push HbA1c up. If your results do not match, ask your GP.
