Iron Deficiency Anemia May Complicate Diagnosis of Diabetes Interview with:
Emma English PhD

Lecturer in Healthcare Science and Academic Lead for Clinical Biochemistry
University of Nottingham, School of Medicine
Royal Derby Hospital, UK

MedicalResearch: What is the background for this study? What are the main findings?

Dr. English: HbA1c is widely used for monitoring glycaemic control in people with diabetes as there is clear evidence that lowering HbA1c values leads to reductions in the rates of diabetes complications. Recently the World Health Organization and the American Diabetes Association have both advocated the use of HbA1c for the diagnosis of Type 2 diabetes at a value of ≥48 mmol/mol (6.5%). Whilst there are many advantages to the use of HbA1c as a diagnostic tool there are equally some significant limitations to its use. A widely cited confounder is anaemia, however to what extent and which types of anaemia affect HbA1c results was not clearly understood. When HbA1c was introduced as a diagnostic test in England we received many queries from healthcare professionals asking questions such as ‘at what level of anaemia should I not use HbA1c?’ and ‘should I routinely screen patients for anaemia when using HbA1c? And if so, what test should I use?’. In order to answer these questions we conducted a systematic review of the literature to determine what was known on this subject.

Our findings, presented in Diabetologia, suggest that iron deficiency and iron deficiency anaemia may lead to a spuriously elevated HbA1c level, thus may lead a false positive diagnosis of diabetes. However, non-iron deficiency anaemias can lead to an artificially lower HbA1c and may lead to a false negative result where a diagnosis of diabetes would be missed. There is no clear evidence to suggest at what levels anaemia can give rise to these effects on HbA1c value and also there does not appear to be a single ideal test for identifying patients where this could be an issue.

MedicalResearch: What should clinicians and patients take away from your report?

Dr. English: Our findings highlight the need to be aware of the potential effects anaemia can have on HbA1c values in both the diagnosis and monitoring of people with diabetes. Unfortunately the opposing effects seen with different types of anaemia mean that simply identifying a low haemoglobin value will be insufficient to know how the HbA1c value will be affected, so it is important to indentify which type of anaemia is present. In addition, iron deficiency without overt anaemia may also be sufficient to affect HbA1c values, a situation that is not uncommon in women of child bearing age.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. English: We recommend that future studies address both iron deficiency and non-iron deficiency anaemias and their potential effects on HbA1c values. In addition it is important to determine the best test or tests to identify patients where anaemia may be an issue. Any future study should also be conducted with HbA1c measurements that are aligned to IFCC (International Federation of Clinical Chemistry and Laboratory Medicine) values, in order to provide robust data.


The effect of anaemia and abnormalities of erythrocyte indices on HbA1c analysis: a systematic review

Emma English1 & Iskandar Idris1 & Georgina Smith1 & Ketan Dhatariya2 & Eric S. Kilpatrick3 & W. Garry John4

Diabetologia DOI 10.1007/s00125-015-3599-3

[wysija_form id=”3″] Interview with: Emma English PhD (2015). Iron Deficiency Anemia May Complicate Diagnosis of Diabetes