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I agree completely with Jonathan Middle's comments about DCCT "standardisation" of methods. I understand the argument that the DCCT method must be kept as a reference because there is so much clinical data that is based upon it. In that case, would it have been acceptable to use an ancient gravimetric technique as a reference method for calcium, simply because the original reference ranges were derived using that method, and then correct the results from more modern techniques forever afterwards? The problem is that the DCCT method was first published in 1985. Chromatography has moved on since then, and there are HPLC methods available which can separate more minor fractions from HbA1c. These fractions co-elute with HbA1c in the DCCT method, so it gives higher results than most other chromatographic methods. The calibrators that some manufacturers provide for "DCCT correction" are lyophilised, yet we know that many methods are affected by the sample matrix (see WEQAS reports). The method I use (in-house : PolyCAT weak cation exchange column) provides virtual baseline separation of HbA1c from the fraction which elutes next, although I know that there is an acetylated fraction which co-elutes with HbA1c, as it does in most HPLC methods. This method still gives results, however, which are 1.0 to 1.5% lower than a "DCCT method". If I add on the percentage area of the fraction which elutes after HbA1c, the results are much closer to "DCCT values"!! Nevertheless, I have been forced into deriving a "fiddle factor" so that we can report "DCCT-corrected" HbA1c values. I can envisage that there will still be problems even after the introduction of a true HbA1c standard by the IFCC. If a chromatographic method suffers from co-elution of minor fractions with HbA1c, then calibration of these will still be a fudge, bearing in mind that there is inter-individual variation in these fractions. We need better methods in addition to a true HbA1c calibrant. Phillip Jordan Clinical Scientist Royal Devon and Exeter Hospital %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%