HbA1c tests and other type 1 diabetes health checks

Most people are aware that type 1 diabetes (T1D) management involves closely monitoring blood glucose levels. But there’s another test you may have heard of, too: the haemoglobin A1c (HbA1c) test.

Here’s what you need to know about HbA1c and how it’s tested, as well as other important tests for people living with T1D.

What is HbA1c?

When you check your blood glucose level (BGL) with blood glucose meter (finger pricks), a continuous glucose monitor (CGM) or flash glucose monitor (flash GM), you’re measuring how many molecules (or mmol) of glucose are in your blood stream right then.

The glucose in your blood stream attaches itself to the haemoglobin part of your red blood cells – and that’s what’s called glycated haemoglobin, or HbA1c. If there’s a lot of glucose in your blood stream, this will result in a higher number of haemoglobin with glucose attached.

About the HbA1c test

As your blood cells (and therefore your haemoglobin) live for around 120 days, your HbA1c result looks at your overall blood glucose control for the preceding two to three months.

The HbA1c test is a blood test, and your doctor or diabetes team will arrange for you to have it every three months.

HbA1c measurements can be reported as percentages (HbA1c as a percentage of total haemoglobin) or the scientific unit of mmol/mol (millimoles HbA1c per mole of total haemoglobin).

What HbA1c result should I aim for?

It’s recommended that adults aim to keep their HbA1c as close to 53mm/mol (or 7%) as possible, as long as this can be achieved without significant episodes of hypoglycaemia.

Research has shown that keeping your HbA1c near this can significantly reduce your risk of developing the long-term complications of diabetes.

Over time, your targets may need to change, so make sure you discuss what your target should be with your diabetes team

HbA1c conversion chart from HbA1c % to system international (SI) units

What about time in range (TIR)?

Now that CGM technology has made it possible to check your blood glucose levels around the clock, you may have heard people talking about time in range (TIR). TIR is a measurement that lets you know what percentage of the day your blood sugars are in your goal range. You might also hear TIR referred to as the hours per day spent in range.

You’ll work with your healthcare team to clarify what your own personal goal range is, but the general recommendation is between 3.9-10.0 mmol/L (while also checking the amount of time you spend with very low glucose levels, or hypoglycaemia).

The more time you spend in range, the lower your chance of developing certain diabetes complications.

So how is TIR different from your HbA1c test? While HbA1c results tell you your average glucose level over the past two or three months, they won’t show how much time you spent in hypoglycaemia or hyperglycaemia, or if your levels are often bouncing from high to low. Your HbA1c gives you an estimate of the middle of your range, but your TIR gives much more insight into daily patterns and how your average glucose level is formed.

Learn more about time in range with Diabetes Australia.

Other regular health checks for people living with T1D

You may be surprised that endocrinologists and GPs don’t just focus on the blood glucose levels or HbA1c levels of people living with T1D. Optimum T1D management also requires a focus on other tests, including blood pressure and cholesterol levels, because the risk of diabetes-related complications is reduced when blood glucose levels, blood pressure and blood fats are kept as close to normal as possible.

• Have your blood pressure checked regularly (at every visit to the doctor) and treated if necessary. For someone with diabetes the target blood pressure reading is 130/80mmHg or lower.
• Have your cholesterol checked every year. The target for total cholesterol is 4mmol/L, with target LDL (bad) cholesterol of <2mmol/L; HDL (good) cholesterol >1mmol/L and triglycerides of <1.8mmol/L.

Read more about regular T1D checks and the healthcare professionals that perform them. 

Goals for optimal type 1 diabetes health management

Source: Diabetes Australia, Diabetes Management in General Practice 15th Edition

This article is adapted from Straight to the Point, your guide to living with T1D as an adult. Download your free copy now.