Link to other blood tests

Prepared by: Mark O'Doherty and Maria Hughes, UKCRC Centre of Excellence for Public Health, Queens University Belfast, United Kingdom

Details of collected information about total and HDL cholesterol assessment in CHANCES cohorts are displayed in attached Excel file .

The ADA in 2011 suggested the use of HbA1C for the diagnosis of diabetes (American Diabetes Association, 2011). A measurement of HbA1C ≥ 6.5% should be diagnostic of diabetes, while a subject with HbA1C between 5.7% and 6.4% should be considered as high risk for developing diabetes in the future. The WHO in 2011 also accepted the use of HbA1C as an "additional" test to diagnosis diabetes (World Health Organization, 2011). However, the WHO concluded that there is currently insufficient evidence to make any formal recommendation on the interpretation of HbA1c levels below 6.5%, but that a cut point of 6.5% is recommended for diagnosing diabetes. Both these reports and the previously mentioned review of OGTT (Bartoli et al, 2011) give a good overview of the current state of knowledge on the use of HbA1C.

Five cohorts can provide data: ESTHER, HAPIEE, NHS, Tromsø, and Zutphen. Only ESTHER and HAPIEE have these measurements at baseline, with ESTHER also having HbA1C measured at recontact 3 (2008-2010). The total cohort was assessed in ESTHER, though the sample size was lower at recontact 3 than for baseline because donation of blood samples at recontacts was voluntary. Also, information on the apparatus used and calibrators applied is currently not known for recontact 3, and the possibility of methodological differences (e.g. differences in the time for which the samples were stored) may make the use of repeated measurements within this cohort challenging. HAPIEE analysed HbA1C in a subsample of their cohort for the Czech Republic, Poland and Russia within 5yr age groups, however further information is current missing. The NHS collected 33,000 blood samples in 1989-90 followed by second samples from 18,700 of these participants in 2000-01. However, HbA1C has only been measured within a select subset of this population (Wei et al, 2006), and therefore it may not be usable in general population analyses. Tromsø T4 has also analysed HbA1C in a subsample of their participants. Those who were invited to a second visit for more extensive examination were selected (all people aged 55-74 years (50-74 in women) and 5-10 % samples of other age groups). Zutphen recontact 2 (1993-1995) has also analysed HbA1C but no further information is currently available.

Unfortunately, not all cohorts have provided sufficient information on the apparatus used and calibrators applied in the measurement of HbA1C. Nevertheless, clear methodological differences exist between the cohorts which may influence comparability of HbA1C levels. Therefore, at this time it is difficult to accurately judge the comparability of the measurements.

Table 7. Haemoglobin A1C

References

American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2011;34 Suppl 1:S62-9.

Bartoli E, Fra GP, Carnevale Schianca GP. The oral glucose tolerance test (OGTT) revisited. Eur J Intern Med. 2011;22:8-12.

Wei EK, Ma J, Pollak MN, et al. C-peptide, insulin-like growth factor binding protein-1, glycosylated hemoglobin, and the risk of distal colorectal adenoma in women. Cancer Epidemiol Biomarkers Prev. 2006;15:750-5.

World Health Organization, 2011. Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus: Abbreviated Report of a WHO Consultation. http://www.who.int/diabetes/publications/report-hba1c_2011.pdf. Accessed 1st August 2011.

hba1c.xls (application/msexcel)