Changing How A1c Values Are Reported

I'm the kind of person who usually embraces change. But only when that change is clearly beneficial or positive in some way., rather than just the pointless act of change for change's sake. My initial reaction to the news that A1c values in the UK will no longer be reported as percentage values is "why?", and I'm struggling to identify a positive reason for the move.

The new unit of measurement will be millimoles per mole, or mmol/mol, rather than existing percentage measures. A current result of 6% will equate to 42mmol/mol, 6.5% to 48mmol/mol and 7% to 53mmol/mol. The unit of measurement presents a potential problem to regions of the world that measure blood glucose in mmol/l, which includes the UK. Since the mole is a fairly obscure scientific measure in everyday use, you can bet a lot of people will be confused by mmol/mol and mmol/l. And if your 3 monthly report suggests your average BG has been 48mmol/l, you're going to be a bit worried!

So why the change? According to the official literature, it will make comparing results from different laboratories easier, but something doesn't add up.

There is no mention of changing the way in which A1c is actually measured, or the calibration and standardisation of results. In fact, the same piece of loiterature states "It is just a different way of expressing the same thing."  The literature intended for healthcare professionals also says that there is no actual change in calibration methods, just in the units to make comparing results to an existing calibration set easier.

But why pass confusion and change on to patients who are used to the current system and clear about their goals and targets? If this is a simple conversion between numbers, why not apply the conversion at the time it's needed? Let the scientists and clinicians convert the existing numbers to the units they want to use instead of asking patients to have to convert their new results into a currency they are familiar with.

Am I missing something?

Comments

[CathyS]

As I understand it, the change is part of an initiative to standardise both the measurement and reporting of Hb1Ac values throughout the world.

In the UK, we already use the standard reference measurement system, so no change is needed to that. But we do need to change the reporting method to bring us into line with the standard.

See this document, if you're interested:

http://www.acb.org.uk/news/default.aspx?ref=177

The change in units might cause confusion in the short term, but surely it will reduce confusion in the long term, as everyone will be using the same units to describe the same thing - thus eliminating the need for conversion.

For example, if it was internationally agreed that blood glucose should be universally measured in mmol/l, wouldn't it make life easier in the long run - even if it took time for those in countries where it's presently measured in mg/dl to get used to it?

As for the possible confusion between mmol/l and mmol/mol, I don't really think this is an issue. It doesn't really matter what the units are - it's the numbers that count. Just as before, we'll have a figure for our target blood glucose and a figure for our target HbA1c - it's just that the latter figure will now be different.