I think the DCA analyzer numbers are directly comparable across clinics throughout the world because the unit provides an internally calibrated number (% HbA1c). Using a kit will produce an "intensity" value that needs to be calibrated back to  % HbA1c in order to be comparable with other numbers. 

Perhaps the value obtained will be comparable to the DCA values, however, is it not more important that whatever measure you choose detects differences between groups inside your study? In other words, if controls are significantly lower than diabetics, then your measures are valid within the study. Now, are those numbers comparable to other numbers obtained with other machine is not really something you are testing scientifically (or is it?).

I do have to admit that the beauty of the DCA analyzer is the tightness of the data. I was able to detect significant differences between groups at 0.3%! I doubt other assay-type measurements are that tight.

Are you able to  try some samples with both methods, perhaps with terminal bleeds where you will have plenty of sample? What does Crystal Chemical say about comparability with other methods? I would love to have known about this Crystal Chem kit a year or two ago when I was measuring HbA1c in rats. I used the A1cNow kits, and they seemed to work but I was only interested in the difference between rats before developing  hyperglycemia and the same rats at a time point afterwards. I did not evaluate the method to know how it compares to other methods.

Hi,

The successful treatment of diabetes depends on keeping blood glucose levels at normal rate over the long term.  Many tests have been developed for this purpose.  While the blood glucose level reflects the current condition of a patient it is inadequate in evaluating the level of glucose regulation. HbA1c level in blood is the most important indicator of the overall glucose level in a patient during a period of two or three months. Ion exchange HPLC method is based on the charge of the globin component of hemoglobin (Hb).

Although it measures all types of Hb and is affected by abnormal and minor Hb fractions, the Diabetes Control and Complications Trial (DCCT) and the National Glycohemoglobin Standardization Program (NGSP) have recommended it as an acceptable standard. Recently, new HPLC systems have been developed using more modern chromatographic materials in order to reduce the effects of abnormal and minor Hb fractions. HPLC is more expensive than turbidimetric immunoassays because it needs more technical staff, expensive equipment and time. On the other hand the HbA1c antibody used in turbidimetric immunoassays reacts only with HbA1c and the result can be measured easily with a turbidimeter. 

Furthermore, these methods are easier to adapt to biochemical devices, cheaper in cost and faster in producing results than HPLC. Despite all these advantages, turbidimetric immunoassays have lower precision than HPLC.

All the best for your study.

I think Senthilvel you have pointed out that HLPC is the more accurate method to use over the turbidimetric immunoassays and how clinically applicable the HbA1c measurement is, thankyou for this.  Here we are looking at rodent models of disease- so working with non-human samples, which are restricted in terms of volume of blood we can obtain and also the timescales of measurement (animal models run typically for a month)- So we want a translatable and relevant marker that the measurement of is sensitive enough to see effects in shorter timescales.  We have performed a direct comparison of samples run in the DCA analyser together with the Crystal Chem kit and what we saw was a slightly larger variability between sample values in the Crystal Chem kit together with a lower overall value which may exclude its use.  We have also outsourced the measurement to 2 independent labs that use the same method on different clinical chemistry analysers and again seen slightly different results but one sample set had been frozen so was not a true comparison.  In terms of expense of the HPLC, we do already have the equipment and staff so I think that this is the next option to explore. Thankyou all for your feedback and input.... 

Yes, i am also agreed with Dr. Senthilvel Vasudevan, here we have new technique named LPLC (Low pressure liquid Chromatography that is as sensitive as HPLC, less expensive, accurate and precise, we have used the same for the detection of HbA1c from mice....its easy to use, just need 5 ul sample.