HbA1c is a perfect diabetes diagnosis

When diabetes is uncontrolled, a excessive proportion of hemoglobin turns into glycated, inflicting HbA1c and glucose ranges to rise within the physique.

Target HbA1c as a medical marker for diabetes

Hemoglobin A1c (HbA1c) is an accepted measure for the diagnosis and continual administration of diabetes.1 Hemoglobin is a protein liable for transporting oxygen all through the physique.

HbA1c measures the share of glycated hemoglobin proteins, a direct measure of how nicely the physique’s glucose ranges are managed.1 If insulin is not correctly secreted in response to elevated glucose ranges, each macro and microvascular issues can happen.

When diabetes is uncontrolled, excessive percentages of hemoglobin are glycated and HbA1c and glucose ranges rise within the physique, resulting in the issues talked about above.1.2

HbA1c can measure glycated hemoglobin traits over the previous 3 months, as the typical lifespan of a purple blood cell (RBC) is roughly 90-120 days.1 Although this laboratory check might be helpful for assessing diabetes management, it is additionally essential to think about circumstances which will have an effect on these indicators.

Conditions that have an effect on HbA1c values

Even if a affected person’s blood glucose stage (BGL) is nicely managed, there are some circumstances that may trigger an elevated HbA1c stage. Some widespread circumstances are listed Table 1. One of them is iron deficiency anemia, which causes a lower within the manufacturing of purple blood cells.3.4

Table 1: Conditions that trigger artificially elevated HbA1c.5

As manufacturing decreases, the imply age of purple blood cells will increase and HbA1c ranges enhance (Figure 1). In normal, any situation that prolongs purple blood cell life could cause a falsely elevated HbA1c.

Figure 1: Mechanism of iron deficiency anemia and HbA1c.

In addition, there are circumstances that shorten the lifetime of the purple blood cell, which ends up in an inaccurate lower within the HbA1c worth. Indicated in circumstances which will falsely decrease HbA1c values Table 2.

Table 2: Conditions that trigger falsely low HbA1c ranges.5

* Lower HbA1c values ​​are anticipated within the second trimester, however might rise within the third trimester

**Elevation is extra widespread than low HbA1c

Note that purple blood cell transfusions might enhance or lower HbA1c values. Changes in HbA1c values ​​depend upon donor blood glucose ranges, as they’ll have a diluting or concentrating impact. High HbA1c values ​​are sometimes noticed as a result of blood transfusions are saved in dextrose options.6

Alternative strategies of glucose management

Other labs could also be thought-about in instances the place HbA1c accuracy is questionable—one choice is fructosamine. It is a measure of circulating proteins comparable to albumin, globulins and lipoproteins which were glycated over the earlier 7-21 days.Figure 2).7

Figure 2. Glycated albumin as a proxy for fructosamine.

Finally, albumin performs the biggest position on this worth as a result of it is essentially the most considerable protein circulating all through the physique. Albumin ranges might be affected by a number of circumstances, together with nephrotic syndrome, superior liver illness, and thyroid illness, additional complicating the consideration of fructosamine as a marker of diabetes management.8

Furthermore, there is no definitive equation for decoding fructosamine because it pertains to HbA1c. Circumstances through which it is cheap to measure fructosamine ranges embody inconsistencies in blood glucose and AbA1c ranges, if it is not attainable to attend 3 months for HbA1c measurement, or if the HbA1c worth is imprecise.

According to the 2022 ADA and 2017 AACE pointers, fructosamine has limitations, comparable to no particular steerage on when or the right way to use it in diabetes.9.10

How to proceed when given an inaccurate HbA1c

If HbA1c is suspected to be inaccurate, it is acceptable to depend on blood glucose ranges or steady glucose monitor (CGM) knowledge to make therapeutic changes for diabetes. Before relying solely on blood glucose readings, think about making certain that the affected person’s fingerstick glucometer offers correct readings through the use of a management answer.

Additional HbA1c readings might be produced inside 3 months, if time is out there and nonetheless appears inconclusive, use CGM knowledge, glucose ranges, or fructosamine.5.11

Although the precise deviations from true HbA1c values ​​for every of those circumstances are unknown, medical judgment needs to be used to evaluate whether or not sufferers have discrepancies of their HbA1c and different medical markers of diabetes management.

Author: Mikaela Den Hartog, PharmD Candidate, University of Minnesota, 2023
Preceptor: Christina Thurber, PharmD, Clinical Pharmacist, Department of Community Internal Medicine, Mayo Clinic


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  2. Sherwani SI, Khan HA, Ehzaimi A, Masood A, Saharkar MK. Value of HbA1c check in diagnosis and prognosis of diabetic sufferers. Biomark Insights. 3 July 2016; 11:95-104. doi: 10.4137/BMI.S38440. PMID: 27398023; PMCID: PMC4933534.
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  8. Danese, Elisa and others. “Advantages and downsides of fructosamine and glycated albumin within the diagnosis and remedy of diabetes.” Journal of Diabetes Science and Technology Vol. 9.2 (2015): 169-76. doi: 10.1177/1932296814567227
  9. American Diabetes Association Committee on Professional Practice et al. “16. Diabetes care within the hospital: Standards of care in diabetes-2022. Diabetes Care Vol. 45, Suppl 1 (2022): S244-S253. doi: 10.2337/dc22-S016
  10. Rodbard, Helena W. and others. “American Association of Clinical Endocrinologists Medical Guidelines for Clinical Practice in Diabetes Management.” Endocrine Practice: Official Journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists. 13 Suppl 1 (2007): 1-68. doi:10.4158/EP.13.S1.1
  11. Henderson, Wendy O et al. “How to evaluate glycemic management if hemoglobin A1c is inaccurate or not interpreted?” Cleveland Clinic Journal of Medicine Vol. 88.2 81-85. February 1. 2021, doi:10.3949/ccjm.88a.19135

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