HbA1c is an imperfect prognosis of diabetes
When diabetes is uncontrolled, a larger proportion of hemoglobin turns into glycated, resulting in increased HbA1c and glucose ranges within the physique.
Goal of HbA1c as a scientific marker of diabetes
Hemoglobin A1c (HbA1c) is a generally accepted measure for each the prognosis and administration of diabetes.1 Hemoglobin is the protein accountable for carrying oxygen all through the physique.
HbA1c estimates the proportion of glycated hemoglobin proteins, which is a direct measure of how effectively the physique’s glucose ranges are managed.1 If insulin isn’t secreted correctly in response to elevated glucose ranges, issues involving each the macro- and microvasculature can happen.
When diabetes isn’t managed, a larger proportion of hemoglobin turns into glycated, inflicting increased HbA1c and glucose ranges within the physique, resulting in the aforementioned issues.1,2
HbA1c can measure glycated hemoglobin traits over the previous 3 months as a result of the common lifespan of a purple blood cell (RBC) is roughly 90-120 days.1 Though this laboratory check may be helpful in assessing diabetes management, it’s also essential to think about situations which will have an effect on these readings.
Circumstances affecting HbA1c
There are some ailments that may trigger a rise in HbA1c though the affected person’s blood glucose (BGL) is effectively managed. A few of the extra widespread situations are described in Desk 1. One in all them is iron deficiency anemia, which results in a lower within the manufacturing of purple blood cells.3,4
Desk 1: Circumstances that trigger falsely elevated HbA1c.5
As manufacturing declines, the common age of purple blood cells will increase, resulting in increased HbA1c ranges (Determine 1). Normally, any illness that will increase the lifespan of purple blood cells could cause a falsely elevated HbA1c worth.
Determine 1: Iron deficiency anemia and the mechanism of HbA1c.
As well as, there are ailments that may scale back the life expectancy of purple blood cells, which results in an inaccurate lower within the worth of HbA1c. Circumstances that may falsely decrease the HbA1c worth are described in Desk 2.
Desk 2: Circumstances that trigger falsely low HbA1c.5
* Anticipate low HbA1c values throughout the second trimester, however could rise within the third trimester
**HbA1c rises extra typically than it falls
Observe that purple blood cell transfusions could enhance or lower HbA1c values. Modifications in HbA1c values rely upon the donor’s blood glucose ranges, as they will have a diluting or concentrating impact. Increased HbA1c values are extra widespread as a result of most blood transfusions are saved in dextrose options.6
Different strategies for assessing glucose management
Different labs could also be thought-about in instances the place the accuracy of HbA1c is in query – one choice consists of fructosamine. It’s a measure of circulating proteins, resembling albumin, globulins, and lipoproteins, which have been glycated over the earlier 7–21 days (Determine 2).7
Determine 2. Glycated albumin as a measure of fructosamine.
In the end, albumin will play the biggest function on this worth as a result of it’s the most considerable protein circulating all through the physique. Albumin ranges may be affected by a wide range of situations, resembling nephrotic syndrome, superior liver illness, and thyroid illness, complicating the usage of fructosamine as a marker of diabetes management.8
Additionally, there is no such thing as a actual equation for deciphering fructosamine in relation to HbA1c. Conditions during which it could be prudent to measure fructosamine embody discordant blood glucose and AbA1c ranges, when ready 3 months to measure HbA1c isn’t potential, or when it’s suspected that the HbA1c worth is inaccurate.
In accordance with the ADA 2022 and AACE 2017 tips, there are limitations to fructosamine, resembling no particular tips on when or tips on how to use it in diabetes.9,10
Methods to act with inaccurate HbA1c
If inaccurate HbA1c is suspected, it could be prudent to depend on blood glucose or steady glucose monitor (CGM) knowledge to information changes in diabetes remedy. Earlier than relying totally on blood glucose readings, be sure the affected person’s meter is giving an correct studying with a management resolution.
A further HbA1c worth may be obtained after 3 months if time permits, and if it nonetheless appears imprecise, then think about using CGM knowledge, glucose ranges, or fructosamine.5.11
Though the precise deviations from precise HbA1c values are unknown for every of those situations, scientific judgment ought to be used to evaluate whether or not there are discrepancies in sufferers’ HbA1c and different scientific options of diabetes management.
Writer: Michaela Dan Hartag, Ph.D., College of Minnesota, Class of 2023
Teacher: Christina Thurber, PharmD, Medical Pharmacist, Division of Inside Medication, Mayo Clinic
- Eyth E, Naik R. Hemoglobin A1C. [Updated 2022 Mar 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; January 2022. Obtainable from: https://www.ncbi.nlm.nih.gov/books/NBK549816/
- Sherwani SI, Khan HA, Ehzaimi A, Masood A, Saharkar MK. The worth of the HbA1c check within the prognosis and prognosis of diabetics. Biomark Insights. July 3, 2016; 11:95-104. doi: 10.4137/BMI.S38440. PMID: 27398023; PMCID: PMC4933534.
- Mehdi W, Tota RD. Anemia, diabetes and continual kidney illness. Diabetes care. 2009 Jul;32(7):1320-6. doi: 10.2337/dc08-0779. PMID: 19564475; PMCID: PMC2699743.
- “Diabetes and Persistent Kidney Illness.” Facilities for Illness Management and Prevention, Facilities for Illness Management and Prevention, 7 Could 2021, https://www.cdc.gov/diabetes/managing/diabetes-kidney-disease.html.
- Radin, Michael S. “Pitfalls in Hemoglobin A1c Measurement: When Outcomes Can Be Deceptive.” Journal of Normal Inside Medication Vol. 29, 2 (2014): 388-94. doi:10.1007/s11606-013-2595-x
- Sugimoto, Takeshi, et al. “Modifications in HbA1c following autologous blood donation for elective surgical procedure in sufferers with diabetes.” Blood transfusion = Trasfusione del sangue vol. 12 Appendix 1, Appendix 1 (2014): s209-13. doi:10.2450/2013.0271-12
- Gounden V, Ngu M, Anastasopoulou C, et al. Fructosamine. [Updated 2021 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; January 2022. Obtainable from: https://www.ncbi.nlm.nih.gov/books/NBK470185/
- Danese, Elisa and others. “Advantages and pitfalls of fructosamine and glycated albumin within the prognosis and therapy of diabetes.” Journal of Diabetes Science and Know-how Vol. 9, 2 (2015): 169-76. doi:10.1177/1932296814567227
- American Diabetes Affiliation Committee on Skilled Follow, et al. “16. Inpatient diabetes care: requirements of take care of diabetes-2022. Diabetes Care v. 45, complement 1 (2022): S244-S253. doi:10.2337/dc22-S016
- Rodbard, Helena W, and others. “American Affiliation of Medical Endocrinologists’ Medical Follow Tips for the Administration of Diabetes Mellitus.” Endocrine Follow: Official Journal of the American Faculty of Endocrinology and the American Affiliation of Medical Endocrinologists Vol. 13 Complement 1 (2007): 1-68. doi:10.4158/EP.13.S1.1
- Henderson, Wendy O, et al. “How must you assess glycemic management when hemoglobin A1c is imprecise or uninterpretable?” Cleveland Clinic Journal of Medication Vol. 88.2 81-85. 1 February 2021, doi:10.3949/ccjm.88a.19135
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