Factors Affecting HbA1c

What is HbA1c?

• Hb1Ac is an important indicator of glycemic control in diabetic patients. 
• It reflects average plasma glucose over the previous eight to 12 weeks. 
• It can be performed anytime of the day and does not require special preparation such as fasting. 
• Although HbA1c is in general a robust marker of glycemia, the result can be unreliable under certain condition. 
• Lists of concomitant disease and conditions that may alter HbA1c result is as listed below. 

Increase	Decrease	Variable
Longer red blood cell life span (May occur due to aplastic anemia, iron or vitamin B12 deficiency)	Shortened red blood cell life span. (May occur with splenomegaly, G6PD deficiency)	Fetal haemoglobin
Hyperbilirubinemia	Hyperlipidemia	Methemoglobin
Uremia	Sickle-cell disease	Certain hemoglobinopathies
Chronic renal failure	Any other condition that could result in premature red blood cell death/blood loss	Alcoholism
	Diabetic and non diabetic pregnant women

• Lists of concomitant drugs that may alter HbA1c  with its proposed mechanism is as listed below. 

Reference : 

1. Speeckaert, M., Van Biesen, W., Delanghe, J., Slingerland, R., Wiecek, A., Heaf, J., … European Renal Best Practice Guideline Development Group on Diabetes in Advanced CKD,  for the E. R. B. P. G. D. G. on D. in A. (2014). Are there better alternatives than haemoglobin A1c to estimate glycaemic control in the chronic kidney disease population? Nephrology, Dialysis, Transplantation : Official Publication of the European Dialysis and Transplant Association - European Renal Association, 29(12), 2167–77. http://doi.org/10.1093/ndt/gfu006
2. Sultanpur, C. M., & Kumar, Sv. (2010). Comprehensive Review on HB1AC in Diagnosis of Diabetes Mellitus. International Journal of Pharmaceutical Sciences Review and Research, 3(2).
3. Unnikrishnan, R., Anjana, R. M., & Mohan, V. (2012). Drugs affecting HbA1c levels. Indian Journal of Endocrinology and Metabolism, 16(4), 528–31. http://doi.org/10.4103/2230-8210.98004
4.  http://www.leicestershospitals.nhs.uk/EasysiteWeb/getresource.axd?
5. http://www.who.int/diabetes/publications/report-hba1c_2011.pdf