Accurate Diabetes Testing: Insights on HbA1c and Blood Sugar Levels

What are the more accurate methods for measuring blood glucose levels?

Hello, doctor.
I recently received my health check report, and the results showed that my fasting blood sugar appears normal, but my glycated hemoglobin (HbA1c) is at 6.0.
In the past, my HbA1c levels were between 5.8 and 5.9, so this increase to 6.0 was quite surprising.
Additionally, I may be a carrier of thalassemia, and my previous health check indicated abnormal red blood cell values as follows.
Could it be that my HbA1c is actually higher than reported? Furthermore, I just remembered that two days before the health check, I accidentally took a 100 mg vitamin C tablet in the morning.
Could this have led to an underestimation of my blood sugar levels in the test results? Thank you.
My abnormal values are as follows: Fasting blood sugar 86, HbA1c 6.0, RBC 6.62, MCV 68.4, MCH 20.3, MCHC 29.6.

Niming, 30~39 year old female. Ask Date: 2022/07/26

Dr. Li Jian reply Internal Medicine

If you are concerned that anemia may affect the accuracy of hemoglobin A1c, you can test for glycated albumin.

Reply Date: 2022/07/26

More Info

When interpreting diabetes testing results, particularly HbA1c and blood sugar levels, it is essential to understand the implications of these values in the context of overall health. Your recent health check results show a fasting blood sugar level of 86 mg/dL, which is within the normal range, but your HbA1c level is 6.0%. This is a slight increase from your previous readings of 5.8-5.9%, and it is understandable that this change has caused you some concern.

Understanding HbA1c and Blood Sugar Levels
1. HbA1c Interpretation: The HbA1c test measures the average blood glucose levels over the past two to three months. An HbA1c of 6.0% is considered to be in the prediabetes range, as the American Diabetes Association defines prediabetes as an HbA1c of 5.7% to 6.4%. Although your fasting blood sugar is normal, the HbA1c indicates that your blood sugar levels may have been elevated on average over the past few months.

2. Impact of Mediterranean Anemia: You mentioned being a carrier of Mediterranean anemia (thalassemia). This condition can affect the accuracy of HbA1c readings. In individuals with certain hemoglobinopathies, the HbA1c test may yield falsely low or high results. Given your abnormal RBC count (6.62 million/µL) and low MCV (68.4 fL), it is possible that your HbA1c could be inaccurately reflecting your average blood glucose levels. It would be prudent to discuss with your healthcare provider whether alternative methods of assessing your glucose control, such as fructosamine testing, might be more appropriate for you.

3. Vitamin C Influence: Regarding your concern about the vitamin C intake prior to your test, high doses of vitamin C can potentially interfere with certain blood glucose tests, leading to falsely low blood sugar readings. However, the HbA1c test is generally not affected by vitamin C. Therefore, while your fasting blood sugar might be influenced by the vitamin C, it is unlikely that it would have significantly impacted your HbA1c result.

Recommendations
- Monitoring: Given that your HbA1c is at 6.0%, it is essential to monitor your blood sugar levels regularly. Maintaining a healthy lifestyle, including a balanced diet and regular physical activity, can help manage your blood sugar levels and potentially lower your HbA1c.

- Consultation with Healthcare Provider: It is crucial to discuss your results with your healthcare provider, especially considering your history of Mediterranean anemia. They may recommend further testing or alternative methods to accurately assess your glucose control.

- Lifestyle Adjustments: Focus on dietary changes that promote stable blood sugar levels, such as incorporating whole grains, lean proteins, healthy fats, and plenty of fruits and vegetables. Regular exercise can also enhance insulin sensitivity and help manage blood sugar levels.

- Follow-Up Testing: Depending on your healthcare provider's recommendations, you may need to repeat the HbA1c test in a few months to monitor any changes. If there are concerns about the accuracy of the HbA1c due to your anemia, they may suggest alternative tests.

In summary, while your fasting blood sugar is normal, the HbA1c level of 6.0% suggests a need for closer monitoring and possibly lifestyle adjustments. Given your unique health background, it is essential to work closely with your healthcare provider to ensure accurate assessment and management of your blood sugar levels.

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