HbA1c Explained: What Your Blood Sugar Test Tells You and Why Pre-Diabetes Deserves More Attention

Reviewed by GPhC Pharmacist at Halton Pharmacy, Leeds

HbA1c is one of the most useful blood tests for metabolic health. It’s also one of the most poorly explained.

Most patients are just told their result is “a bit high” or “borderline.” They get a diet leaflet. They leave without really understanding what the number means.

That’s a problem. The gap between a normal result and a diabetes diagnosis is one of the most important windows in your health journey. Understanding it can genuinely change your future.

What Does HbA1c Actually Measure?

HbA1c stands for glycated haemoglobin. In plain terms:

• Haemoglobin is the protein in your red blood cells that carries oxygen.
• Glucose (sugar) in your blood attaches to it over time.
• The more sugar in your blood, the more it attaches.
  
  

Why this test is so useful:

• Red blood cells live for about 8–12 weeks.
• So HbA1c shows your average blood sugar over the past 2–3 months not just right now.
• A single sugary meal or a stressful morning won’t skew the result, unlike a same-day glucose test.
  
  

How it’s measured:

• As a percentage (%)  the older method
• As mmol/mol  the standard UK measurement today
• Both are used, and conversion charts are easy to find.
  
  

The Three Key Ranges

 Note: If you have no symptoms, a single result of 48+ isn’t enough for a diagnosis — it needs a repeat test to confirm. If you do have symptoms, one result may be enough.

Important: These ranges are guides for action, not hard cut-offs. Risk rises steadily across the whole scale. A result of 40 carries more risk than a result of 35 even though both count as “normal.” What matters most is the trend over time, not one single number.

Pre-Diabetes: Why It Deserves More Attention

Pre-diabetes means your blood sugar is higher than normal, but not high enough for a diabetes diagnosis yet.

• It affects around 7 million people in the UK.
• Most of them don’t know they have it.

The word “pre” makes it sound harmless. It isn’t. Here’s why:

1. Pre-diabetes already carries real risks

• Higher risk of heart disease, even before diabetes develops.
• Ongoing high blood sugar can damage blood vessels.
• Increased risk of kidney and nerve damage — problems once thought to only happen after a diabetes diagnosis.
• Often comes with other issues too: high blood pressure, high cholesterol, and weight gain around the middle.

2. It can progress to type 2 diabetes — but doesn’t have to

• Without action, 5–10% of people with pre-diabetes develop type 2 diabetes every year.
• Over 10 years, many will cross that line.

But this is reversible. A major trial (the Diabetes Prevention Programme) found:

• Lifestyle change (diet + exercise, aiming for a 7% weight loss) cut progression to diabetes by 58% over 3 years.
• Metformin (a common medication) cut it by 31% — still helpful, but less effective than lifestyle change alone.

This makes pre-diabetes one of the most reversible stages in the whole disease process — and the best time to step in.

What Affects Your HbA1c Level?

What you eat

• Regular high-sugar, high-refined-carb meals raise HbA1c over time.
• Fibre and overall diet quality matter more than any single food.

How active you are

• Muscles use up blood sugar for energy.
• Exercise even just more daily walking improves how your body handles sugar.

Your weight

• Extra weight around the middle is linked to insulin resistance.
• Losing even a small amount of weight can meaningfully lower HbA1c.
• This is part of why GLP-1 weight loss medications also improve blood sugar control.

Health conditions that can distort results Some conditions can make HbA1c inaccurate either falsely high or falsely low:

• Anaemia (including iron deficiency)
• Blood disorders like sickle cell disease or thalassaemia
• Recent blood transfusion
• Pregnancy

If any of these apply to you, other tests (like fructosamine or a glucose tolerance test) may give a clearer picture.

What to Do If Your Result Is 42–47 mmol/mol

Don’t just wait and watch. Take action:

• Adjust your diet
• Get more active
• Manage your weight if needed
• Get retested regularly to track your progress

At Halton Pharmacy in Leeds, our Heart & Metabolic Health Hub offers HbA1c testing as part of a full metabolic health check. If your result shows pre-diabetes or high glucose, we’ll:

• Explain your results clearly
• Give you practical lifestyle guidance
• Tell you if a GP review is needed
• Support weight management alongside it, if that applies to you

A pre-diabetes result isn’t a life sentence it’s a chance to act. The evidence for early intervention working is some of the strongest in all of preventive medicine.

This article is for general information only. It’s not personal medical advice. HbA1c results should always be reviewed by a qualified clinician who knows your health history. Book an appointment for a full metabolic health assessment at Halton Pharmacy, Leeds.