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10th June 2009
From 1st June 2009, glycated haemoglobin (HbA1c) in all people with diabetes will be measured in millimoles per mol (mmol/mol) as well as by percentage (%), the Department of Health have announced. Measurements will be reported in both ways until 31 May 2011 when people with diabetes will receive their HbA1c measurement only in millimoles per mol.
Action
Health professionals need to understand this change, so as to be able to reassure patients and become familiar with the new units in anticipation of the switchover in 2011.
What is the background to this?
Glycated haemoglobin is the recommended method of measuring long term control of blood glucose in people with both type 1 and type 2 diabetes. The UK is responding to the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) call for all countries to adopt the same measurement to make it easier to compare HbA1c results between laboratories throughout the UK and worldwide. The Diabetes UK website has useful information about the change, including an online converter.
Both the old and the new measurements will be given for the first two years of the change, until 31 May 2011, when people with diabetes will receive their HbA1c measurement only in millimoles per mol. More information is provided in Diabetes UK-produced leaflets for health professionals, for patients, and for laboratory staff.
So what?
There is a linear relationship between HbA1c as a percentage and as millimoles per mol. A 0.5% difference in HbA1c is equivalent to a difference of about 5.5mmol/mol, and a 1% difference is equivalent to a difference of about 11mmol/mol. Note that these are rounded equivalents. The table below gives some common values, taken from the leaflet for laboratory staff.
|
HbA1c % |
HbA1c mmol/mol |
|
4.0 |
20 |
|
5.0 |
31 |
|
6.0 |
42 |
|
6.5 |
48 |
|
7.0 |
53 |
|
7.5 |
59 |
|
8.0 |
64 |
|
9.0 |
75 |
|
10.0 |
86 |
More information on the management of people with type 1 diabetes and type 2 diabetes can be found on the relevant floors of NPC. NICE has also recently partially updated its guidance on the management of type 2 diabetes (to give advice on use of newer drugs) – see our blog.
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