Blood tests

An HbA1c test is a blood test that shows your average blood glucose level over the last 2–3 months. It does this by measuring how much glucose is stuck to a protein in your red blood cells called haemoglobin.​

Your red blood cells live for about 2–3 months, so the test gives a picture of how high or low your blood glucose has been over that time, not just on one day. A higher HbA1c number means there has been too much glucose in your blood for a long time, and this can increase the risk of problems with your eyes, kidneys, nerves and heart.

There are slight variations between diagnostic numbers for labs and countries, so always refer to what your doctor advises. The numbers below give a general guide.

Non-diabetic HbA1c:
< 5.5 – 5.7 mmol/L (AU)
< 42 mmol/mol (NZ)

Prediabetic HbA1c:
5.7 – 6.9 mmol/L (AU)
42 – 47 mmol/mol (NZ)

Diabetic HbA1c:
> 7.0 mmol/L (AU)
> 48 mmol/mol (NZ)

Fasting blood glucose:
< 5.5 mmol/L (AU and NZ)

*New New Zealand HbA1c thresholds from July 2026

Diabetes auto antibodies

As mentioned earlier, diabetes autoantibodies are what cause type 1 diabetes and LADA. They attack the pancreas, causing damage and preventing it from producing insulin.

There are currently five known diabetes antibodies: GADA/GAD-65, IA-2A, ZnT8, IAA, and ICA.

Antibody testing can be used to diagnose or rule out LADA in people over 30 years old, particularly if blood glucose is not responding as expected to diet, lifestyle changes, and medical interventions.

This is especially relevant for those who are lean, have a normal BMI, no metabolic conditions, and a family history of autoimmune disease, as these presentations are more indicative of LADA than type 2 diabetes. These are generally specialist-level tests, which means they should often be ordered by an endocrinologist (a specialist with a focus on conditions involving hormones, including diabetes), rather than a GP.

Self-testing with a finger-prick test

It’s important to remember that a normal bodily response is for blood glucose levels to rise and fall. In fact, they fluctuate throughout the day. Since insulin is a hormone that responds to other hormones, it is always changing as well. This is normal.

There are ideal ranges within which these fluctuations should stay, but the goal is never to ‘flatline’ blood glucose. That is not biologically normal or possible. The aim is to improve insulin sensitivity or diabetes management so that blood glucose fluctuations stay within, or as close as possible to, a normal and therefore safe range.

People with type 1 diabetes and those with insulin‑dependent diabetes need to monitor their blood glucose levels regularly.

People with type 2 diabetes generally only need to monitor their blood glucose if they are taking insulin or other medications that may cause low blood glucose levels, or if advised to do so by their healthcare practitioner. If your healthcare practitioner or diabetes educator has advised you to monitor your blood glucose, please read more here.

Data is very useful for your doctor and healthcare team. It can be helpful to document your BGLs testing with dates, time of day and amount of time post-meal to share with your doctor to help show progress and spot patterns. For example:

Continuous glucose monitor

A continuous glucose monitor (CGM) is a small device that tracks your glucose levels all day and night without repeated finger-prick tests. A tiny sensor sits just under the skin (usually on the arm or belly) and measures glucose in the fluid around your cells every few minutes. The sensor sends these readings to a phone, reader, or insulin pump so you can see your glucose level and how it changes with food, activity, medications, and sleep.

Many CGMs can also sound alerts if your glucose goes too low or too high, helping you act quickly to stay in a safer range.

You should feel confident and knowledgeable about wearing and understanding your CGM. If you would like more support or information, ask your healthcare practitioner to connect with a diabetes educator, and if you experience frequent high or low BGLs (in particular low BGLs overnight), let your doctor and/or diabetes educator know as soon as possible, and ask if it may benefit you to have a CGM with alarms.

CGMs are not as accurate as finger-prick tests and have about a 15-minute delay, so best practice is to always double-check a CGM reading with a finger-prick test, especially when making decisions related to blood glucose management and insulin dosing.

Read here for more information on CGM time in range expectations.

CGMs are not recommended for people without diabetes and should only be used when prescribed by a medical professional. Research from the University of Bath found that CGMs can significantly overestimate the amount of time blood glucose is above recommended levels—by nearly 400% in one study—which may distort someone’s perception of their health and lead to unhelpful or harmful dietary changes.

Hypoglycaemia

When blood glucose levels drop below 4 mmol/L in people with diabetes, it is called hypoglycaemia (also known as a hypo or low blood glucose level). Hypoglycaemia can occur in people who use insulin and some other glucose-lowering medications. It is important to treat a hypo quickly to stop your blood glucose level from dropping even lower. You should always carry hypo treatment with you.

It is very important that you and your loved ones know how to recognise and treat hypoglycaemia. Learn more here and speak to your doctor or diabetes educator if you have questions or are experiencing hypoglycaemia.