HbA1c is used for assessing glycaemic control in patients with diabetes. It is also used for treatment goals and as a target for therapeutic intervention. The Direct Control and Complications Trial in the USA showed that HbA1c can be used to predict the risk of complications. Hence, it is important for HbA1c assays to be standardised. The National Glycohemoglobin Standardization Program (NGSP) in the USA was formed in 1996 so that HbA1c results from different laboratories would be comparable to those reported in the DCCT study. There were also HbA1c standardisation programmes in Sweden and Japan. These three standardisation programmes are, in fact, direct comparison methods (DCMs), and yield different HbA1c results. In 1994, the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) established a Working Group on Standardisation of HbA1c. This working group has developed a global HbA1c reference system with very much improved intra-assay and inter-assay coefficients of variation. Recommendations have been made to report HbA1c results as IFCC-HbA1c values in SI units (mmol HbA1c/mol Hb) and NGSP-HbA1c (%) as well as estimated average glucose (eAG), once a tight relationship has been shown to exist between eAG and HbA1c.
Matched MeSH terms: Blood Chemical Analysis/standards*
HbA1c measurement is currently routinely used to predict long term outcome of diabetes, thus playing a fundamental role in the management of diabetes. The relationship between HbA1c value and long term diabetic complications has been established by a randomised control Diabetes Control and Complications Trial (DCCT) which used high performance liquid chromatography (HPLC) as a reference method for HbA1c assay. To ensure that HbA1c results from a variety HbA1c assay methods are similar to the DCCT values, the American Diabetes Association (ADA) recommended that all laboratories should use methods certified by the National Glycohemoglobin Standardization Programme (NGSP) with interassay coefficient variation (CV) of < 5% (ideally < 3%). The International Federation of Clinical Chemistry (IFCC) working group on HbA1c standardisation has set a CV < 2.5% as a criteria for its reference laboratories.
Matched MeSH terms: Blood Chemical Analysis/standards*