HbA1c: the longer view of blood glucose

Understanding HbA1c

HbA1c (glycated haemoglobin) is a blood test that estimates your average blood glucose over roughly the preceding two to three months — a longer view than any single finger-prick reading can give.

Haemoglobin is the protein inside red blood cells that carries oxygen around the body. When glucose circulates in the blood, some of it attaches to haemoglobin and stays attached for the life of that red blood cell, which is typically around three months. The more glucose has been circulating, the more of it sticks. HbA1c measures the proportion of haemoglobin that glucose has attached to, giving a running average rather than a snapshot — which is why it is used differently from a home glucose reading, and why the two are not interchangeable.

A few things can affect how accurately HbA1c reflects your glucose pattern, and it is worth mentioning them to your clinician: conditions that shorten or lengthen the life of red blood cells (such as some forms of anaemia), pregnancy, kidney disease, and recent significant illness or blood loss can all influence the result.

Why this test is used

HbA1c serves two related but distinct purposes:

• ●Diagnosis. Alongside symptoms and other blood tests, HbA1c can help identify diabetes or prediabetes, sometimes before symptoms appear.
• ●Monitoring. In someone already living with diabetes, HbA1c checked periodically shows whether the overall glucose pattern is improving, stable or worsening, guiding whether treatment needs to change.

HbA1c is different from — and complements — other ways of checking glucose. A fasting glucose test measures the blood sugar level at one moment after not eating for several hours; a random glucose test measures it at any time; a home glucose meter or continuous sensor shows moment-to-moment readings you can act on immediately. HbA1c does not replace any of these; it adds the longer-term pattern that a single reading cannot show, which is why your clinician may use more than one of these tests together.

What the numbers mean

HbA1c is reported as a percentage, and sometimes also in mmol/mol. Commonly used categories, applied alongside your overall clinical picture rather than in isolation, are approximately:

• ●Below 5.7% — within the range generally considered normal
• ●5.7% to 6.4% — a range often described as prediabetes, meaning higher-than-normal risk that has not yet crossed into diabetes
• ●6.5% and above — a range consistent with diabetes, usually confirmed with a repeat test or additional criteria

These are general reference categories, not a diagnosis on their own — your clinician interprets your result alongside symptoms, other blood tests and your personal history. If you are already being treated for diabetes, your individual target may sit above or below these general categories, set specifically for your age, other health conditions and risk of low blood glucose (hypoglycaemia). There is no single "right" number that applies to everyone.

What raises the risk of a high result

Several factors make a raised HbA1c more likely, and are worth mentioning to your clinician even before any test is done:

• ●Overweight or obesity, particularly weight carried around the waist
• ●A largely sedentary lifestyle
• ●A family history of diabetes
• ●High blood pressure — very common in Nigeria, and frequently found alongside raised glucose
• ●A previous diagnosis of prediabetes, or diabetes during pregnancy
• ●Increasing age
• ●Certain medicines, including some steroids

Why the long-term pattern matters

An occasional high reading rarely causes harm on its own. The concern with HbA1c is what a sustained high average, over months and years, does to blood vessels throughout the body — which is also why a heart hospital pays close attention to it.

Prolonged high glucose can damage the delicate lining of small blood vessels, contributing over time to eye disease that can threaten sight, kidney disease, and nerve damage that can reduce sensation in the feet and increase the risk of unnoticed injury. It also accelerates damage to larger blood vessels, raising the risk of heart attack, stroke and reduced circulation in the legs — the reason diabetes and cardiovascular risk are so closely linked, and why glucose control is part of protecting the heart, not a separate concern from it.

Getting your results

• ●A result may be used for diagnosis, or to review how existing treatment is working
• ●Your personal target is not identical to anyone else's — it is set for your circumstances
• ●A change in HbA1c should be discussed alongside your home glucose readings, not viewed alone
• ●Feeling well does not always mean your glucose pattern is safe — diabetes can progress with few or no symptoms, which is exactly why the test is useful

How Cardiocare builds the full picture

HbA1c is rarely read in isolation. A fuller assessment may include:

• 01
  Laboratory HbA1c. A standard venous blood test, unaffected by whether you have eaten beforehand.
• 02
  Home or clinic glucose review. Finger-prick or continuous readings that show the day-to-day pattern behind the average.
• 03
  Medicine, nutrition and activity review. Checking whether current treatment, diet and activity are matched to your target.
• 04
  Screening for diabetes complications. Kidney function, eye examination, foot assessment and cardiovascular risk review, since diabetes affects more than blood glucose alone.

Is this an emergency?

HbA1c itself is a slow, averaged measure — it is never an emergency result on its own. But it can uncover a condition where day-to-day glucose control matters urgently. If you notice the following, do not wait for a booked appointment:

• ●Confusion, drowsiness or difficulty staying awake
• ●Fast, deep breathing with a fruity-smelling breath, or persistent vomiting
• ●Severe dehydration, or collapse
• ●Any severe symptom you are worried about, whatever the cause

Go to the nearest emergency department immediately — do not drive yourself. Call Cardiocare's 24/7 emergency line on +234 806 142 4614 (staffed around the clock) to tell us you are coming.

Practical next steps

• ✓Ask what target applies specifically to your health situation, and why
• ✓Keep a simple home glucose record between visits if advised
• ✓Take treatment consistently, even during periods when you feel well
• ✓Attend kidney, eye and foot reviews as advised, since these catch complications early
• ✓Build activity and dietary changes into daily life gradually, in a way that fits Nigerian meals and routines, rather than as a short-term fix

Preparing for your appointment

What to bring

• ✓Your home glucose diary or meter, if you keep one
• ✓A list of all medicines you take, including herbal and over-the-counter preparations
• ✓Any previous HbA1c or glucose results
• ✓Your HMO card and a valid means of identification

What we will ask

How you have been feeling, any symptoms of high or low glucose, your diet and activity pattern, and how consistently you have been able to take prescribed treatment.

Questions worth asking us

• ●What is my personal HbA1c target, and why?
• ●How does this result compare with my last one?
• ●Does anything about my result change my treatment?
• ●When should this test be repeated?