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International Consensus Reached on Reporting Hemoglobin A1c Values

Laboratory reporting of hemoglobin A1c should be standardized worldwide using two sets of units, according to a joint consensus statement from five professional societies.

The statement calls for HbA1c results to be reported by clinical laboratories in Système International (SI) units (mmol/mol – no decimals), and derived National Glycohaemoglobin Standardisation Program (NGSP) units (% – one decimal). The HbA1c value will be derived using a master equation to convert it to the familiar currently used units (i.e. 6.0%, 7.0%).

HbA1ctest results should be standardized worldwide, and HbA1c conversion tables including both SI and NGSP units should be easily accessible to the diabetes community, according to the statement, endorsed by the American Diabetes Association, the European Association for the Study of Diabetes, the International Diabetes Federation, the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC), and the International Society for Paediatric and Adolescent Diabetes.

Editors of journals and other printed material are strongly recommended to require that submitted manuscripts report HbA1c in both sets of units.

This issue arose several years ago, when the IFCC adopted a new standardized reference measurement system for HbA1c with higher specificity than the previous one. Rather than causing confusion by switching to the new, lower values for HbA1c, it was decided to use the SI values (mmol/mol), along with the converted HbA1c values.

There has also been discussion about using an “estimated average glucose” value which would be reported in the familiar glucose units mg/dL or mmol/L, but not all populations have been evaluated adequately in order to be able to do that. The consensus recommendations apply through 2011, when they will be discussed again at the next consensus meeting at the International Diabetes Federation meeting in Dubai December 2011, the statement says.

European Association for the Study of Diabetes (EASD) Statement:

2010 Consensus Statement on the Worldwide Standardisation
of the Haemoglobin A1c Measurement
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