Can iron deficiency anemia cause a false high A1C test?

Short answer: Yes. However, two consecutive A1c tests of 5.7-6.4 meet the definition of prediabetes (also fasting glucose of 100 or above). Many PCPs are starting to treat vs. ignore prediabetes to delay progression. Low doses of Metformin ER (500mg, extended release) are usually well tolerated, and it is a very cheap medication. Will probably lower your A1c to normal range. Stay away from Immediate Release Metformin since 50%+ who try it have diarrhea as a side effect. Most PCPs know that and would not prescribe IR for prediabetes.

There is no benefit in taking another A1c until several months after the Iron anemia is resolved. The 6.4 is accurate but the comparison of what is normal does not exist for someone with iron anemia since that extends the average lifespan of red blood cells resulting in more glycated cells.

I asked AI. Here is the computers answer.
These are results for what medicines contribute to a high or false A1C reading
Search instead for what medicines contributate to a high or false A1C reading
AI Overview
Certain medications can cause a false A1C reading or genuinely elevate blood sugar, making diabetes management tricky.
To determine if a medication is altering your A1C, it's essential to know if it's interfering with the test itself (causing a false lab result) or actually raising your glucose levels in your body.
Common culprits that impact A1C include:
Medications that Raise Blood Sugar (True Hyperglycemia)

Corticosteroids: Drugs like prednisone raise liver glucose production and cause insulin resistance.
Thiazide Diuretics: Blood pressure medications like hydrochlorothiazide can elevate blood sugar.
Beta-Blockers: Heart and blood pressure medications (e.g., metoprolol, atenolol) can affect insulin release and glucose delivery.
Antipsychotics: Medications such as clozapine and olanzapine increase blood sugar, partially by inducing weight gain.
Other Drugs: Birth control pills, certain HIV and Hepatitis C treatments, and high doses of niacin (Vitamin B3) can also elevate glucose.

Medications that Interfere with the A1C Test (False Readings)

High-dose Vitamin C and E: Can skew A1C results depending on the specific laboratory testing method used (such as electrophoresis vs. chromatography).
Salicylates and Opioids: Long-term or heavy use of aspirin and opiates can sometimes interfere with the assay, causing a false high.
Iron, Vitamin B12, or Folate Supplements: While these correct false highs caused by red blood cell issues (like anemia), starting them can cause fluctuating, temporary readings.

Dapsone and Ribavirin

Hemolysis-inducing drugs: These medications destroy red blood cells faster than normal. Because A1C measures sugar coating on red blood cells, a shorter cell lifespan generally leads to a falsely low A1C result.

20 years ago I was diagnosed as pre diabetic. A1c just above normal and just was a little over the 2 hour point on the glucose tolerance test. I was started on metformin for a while. Fermented foods help with the gas and diarrhea.

I’m not taking it anymore since my A1c is always about 5.7 and my fasting and nighttime glucose readings are from 80-110 mg/%. One thing I learned by experience is the glucose readings can differ between hands by almost 30 mg/%.

What iam hearing is not a good choice , you shouldlook into before you take it. I causes dementia they are finding out about this. Iam Majo

@mamajo9

@mamajo9 i also have same problems my dr. Never ordered ,just said watch yr diet. Some things cause ups and downs.

@annieroosie welcome to Mayo Clinic Connect. The A1C (aka glycosylated hemoglobin or HbA1C) is very basically a sampling of your red blood cells (hemoglobin) that have glucose stuck to them. It gives a good estimate of how your blood sugar has been over a 3 month period of time.

There are various kinds of anemia. A common one is caused by iron deficiency. This often results in changes in the amount of hemoglobin there is. So it is only natural that the A1C would be affected.

My background is 51 years of insulin dependent diabetes and some hypertension (high blood pressure) in my history. Diabetes and hypertension are the two most common causes of kidney problems. I have chronic kidney disease (CKD). I also have anemia. My nephrologist says that this is common among his kidney patients. In the past I have had oral iron supplements prescribed to me and even IV iron infusions.

You mentioned gout, hypertension, iron deficiency anemia, A1C results, kidney function results, ibuprofen and Metformin in your description of yourself. These things all sound like the specialties of endocrinologists and nephrologists. I have nothing against a PCP, but sometimes you need more.

May I ask why are you watching your kidney results and A1C in the first place? Could you ask your PCP if you could benefit from referral to nephrology &/or endocrinology? An endocrinologist could provide valuable input regarding the use of Metformin. A nephrologist could help you understand and treat the iron deficiency anemia. If you aren’t satisfied with the PCP answer perhaps you could self refer.

Will you keep us posted on your progress? Here’s hoping you get some answers and find the best treatment plan possible for your situation.

@cehunt57 ---Can't self refer on my Medicare Advantage plan and PCPS are rushed and time limited. The whole system is a mess.

Thank you all for your responses and comments. I appreciate your interest and willingness to share your experiences. It’s very helpful as I try to get a better understanding of prediabetes, A1C, and glucose testing.