HbA1c: converting old to new

A brand new scale, yesterday

Having had to resort to Dr Google to translate my latest HbA1c result into something meaningful, I thought it might be useful to publish a conversion table for new HbA1c measurements. Since October 2011 the way HbA1c results are expressed has changed – from % to mmol/mol. Mostly this has been done to mess with your head, but there is also a secondary reason about trying to standardise measures all around the world to make it easier to compare results from different laboratories and research trials.

Given the UK has been trying to shift from imperial to metric measurement since 1965 yet many people still respond to the question “how many metres is that?” with “about 3 feet” I’m thinking these changes may take a little while to sink in. So ShootUp has a handy guide.

Ye olde HbA1c measurement (%)       Shiny new IFCC HbA1c measurement (mmol/mol)
6.0                                                                           42
6.5                                                                           48
7.0                                                                           53
7.5                                                                           58
8.0                                                                           64
9.0                                                                           75

If you have a calculator to hand, you might want this handy formula to convert your own numbers:

New mmol/mol = [Old % – 2.15] x 10.929
Old % = [New mmol/mol divided by 10.929] + 2.15

So if your new number is 53, divide it by 10.929, then add 2.15 and round up a bit to discover that’s roughly 7% in old money.

And if your old number was 8% and you want to know what that means in the new world, take away 2.15 and then multiply the result by 10.929 to become enlightened.

Or you could use Diabetes UK’s handy HbA1c converter.