The comparison of HbA1c and Fasting Blood Glucose for the diagnosis of Type 2 Diabetes Mellitus in a Port Moresby Urban population.

 

A pilot study by Dr. Poyap James Rooney, MBBS, MMed Candidate 2014

Supervisors

  1. Dr. Mere Kende – Head of Pathology – UPNG, SMHS

  2. Dr. Francis Bannick – Pathology coordinator – Port Moresby General Hospital

  3. Dr. Steve Andersen – External Examiner

Background

The HbA1c test has been used since the mid 1980’s and is now universally accepted as the most reliable means of monitoring long-term glycaemic control and has become indispensible in any modern diabetes clinics.

More recently the usage of HbA1c as a diagnostic tool has been accepted by several large organisations including the American Diabetes Association (ADA), International Diabetes Federation (IDF) and the WHO.

Considering all the advantages and disadvantages of the use of HbA1c the WHO recommendation is that:

HbA1c can be used as a diagnostic test for diabetes providing that stringent quality assurance test are in place and assays are standardised to criteria aligned to the international reference values, and there are no conditions present which preclude its accurate measurement”.

Aim of the study

The aim of this study is to assess the performance of the HbA1c as a diagnostic test for diabetes in comparison with the fasting blood glucose test.

Method

  1. Screening of individuals will be done at Port Moresby General Hospital and several major business houses in Port Moresby. Individuals who have never been diagnosed previously with diabetes mellitus and who are identified as having either unequivocal diabetes or those that require a 2nd test on a different occasion to either confirm or rule out diabetes will be recruited for the study. These individuals will have a spot HbA1c test done using the Afinion AS100 analyser and a mutually agreed time and place will be arranged to perform a fasting blood glucose test.

  1. Individuals who have discrepant result between the HbA1c and the Fasting Blood Glucose for the diagnosis of diabetes will have an oral glucose tolerance test (OGTT) (used as a gold standard) to confirm and the results will be used to further assess the performance of the tests.

Results

The different test will be correlated against each other and the performance of HbA1c as a diagnostic test assessed. This is a pilot study and will form the basis of a much larger population study in the near future. It is also hoped that this study will spur a renascence of diabetes research in the country which has seen paucity in the last decade

Free diabetes test PMGH

About Dr. Poyap J Rooney

Dr. Rooney is a medical doctor who has gained both his undergraduate medical degree and more recently his post graduate masters degree in clinical biochemistry at the University of Papua New Guinea.
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3 Responses to The comparison of HbA1c and Fasting Blood Glucose for the diagnosis of Type 2 Diabetes Mellitus in a Port Moresby Urban population.

  1. Paulus Ripa says:

    Poyap,
    Excellent going. Just 2 questions; if you are usingHBA1c as a diagnostic test what gold standard are you using? Is it the Fasting blood glucose and if it is so is appropriate?. Settling discrepant results with OGTT seems to raise the issue that you are only doing it on what may be a biased subset of the sample. Why not OGTT in all or compare with a cohort with non-discrepant results?

    Secondly, how are you going to compare results HbA1c with FBG? A correlation test would not bet the proper test; perhaps a Bland-Altmann test.

    Cheers
    Paulus

    • Thanks Paulus!

      Yes I am using FBSL as the gold standard and I am purposely going out looking for individuals who actually have a high risk of having diabetes (so yes I am purposely being bias). HbA1c is well accepted by WHO, World federation of diabete, American association of diabetes etc as a diagnostic tool for DM with 6.5% being the most frequently used cutoff. I agree that ideally OGTT should be the gold standard but in practicle term OGTT is almost never used these days in PNG so I am using the FBSL as the proxy gold standard…

      I am comparing HbA1c with the “established” means of diagnosing DM in PNG. The practical implications here is that it can be used on the spot on the first visit without any need for patient preparation, fasting etc… there is no need for him/her to return for a 2nd visit in order to make a firm diagnosis.

      I think I will need to pay you a visit to seek advise about statistical test etc…

      Cheers mate!

  2. Paulus Ripa says:

    Poyap,
    I would be stealing your money for statistical tests as I am not a statistician. I am more interested in the study design. No I was not suggesting that OGTT would be the gold standard; only the rationale for using it to decide on the discrepant results between FBG and HBA1C as I understand a certain proportion of OGTT results are not reproducible and therefore may have questionable reliability as a gold standard if a one off OGTT is done. If so is there a need to rely do OGTT at all?

    I suspect that HbA1C not only would be useful in diagnosis of diabetes but would also more reliably identify those with impaired GT who may or may not have an abnormal FBG at a given point in time

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