Glycated Hemoglobin: Key Questions for Diabetes Management

Q: Glycated Hemoglobin: Key Questions for Diabetes Management

Dear Ms. <br>Chen：<br>1. <br>The measurement of fasting plasma glucose in clinical practice refers to the plasma glucose level after fasting for more than 8 hours. <br>The normal value is below 100 mg/dL; if it falls between 100 and 125 mg/dL, it is termed impaired fasting glycem

Glycated hemoglobin

Hello Doctor, I would like to ask you about glycated hemoglobin.
There is a family history of diabetes, and I have been vigilant and actively exercising and controlling my diet since December of last year.
My height is 155 cm, and my weight has decreased from 67 kg to the current 58 kg.

1.
When I go for a fasting blood glucose test, does it need to be at a fixed time? I have noticed that when I wait a bit longer after waking up, my fasting levels are lower.
Should I have a fixed time for the blood draw to ensure accuracy?
2.
My fasting blood glucose levels range between 86 and 95 (all from blood tests).
Is this considered high?
3.
My glycated hemoglobin levels fluctuate between 5.0% and 5.2%.
I read that a level above 5.2% indicates a higher risk for diabetes, which makes me a bit worried.
Is it reasonable for glycated hemoglobin levels to vary?
4.
If I start taking metformin, how long should I expect to wait before seeing results?
Thank you for your response, Doctor.

Ms. Chen, 30~39 year old female. Ask Date: 2016/03/26

Dr. Xiao Yongxun reply Internal Medicine

Dear Ms.
Chen:
1.
The measurement of fasting plasma glucose in clinical practice refers to the plasma glucose level after fasting for more than 8 hours.
The normal value is below 100 mg/dL; if it falls between 100 and 125 mg/dL, it is termed impaired fasting glycemia.
For most individuals, plasma glucose levels tend to stabilize after fasting for 8 hours.
However, sudden events that lead to increased adrenaline secretion, heightened stress, the presence of infections, or the effects of other medications can certainly cause blood glucose levels to rise.
Similarly, physical activity can lead to a decrease in blood glucose levels.
Nonetheless, whether elevated or lowered, most individuals will maintain levels around 60 to 100 mg/dL.
You mentioned that waiting a bit longer after waking up before having your blood tested might result in lower blood glucose levels, which is certainly possible; as long as it does not drop too low, it should be fine.
2.
A fasting glucose level between 86 and 95 mg/dL is considered normal.
3.
A hemoglobin A1c (HbA1c) level of 6.5% or higher raises suspicion for diabetes.
If the HbA1c value is between 5.7% and 6.4%, it indicates an increased risk for diabetes.
Your HbA1c level, which falls between 5.0% and 5.2%, is within the normal range.
The HbA1c value reflects average blood glucose levels over a longer period and typically shows a decrease about six weeks after medication initiation or adjustment for diabetes management.
Therefore, if you read that an HbA1c value above 5.2% indicates a high-risk group for diabetes, there may be a misunderstanding.
4.
The pharmacological action of Metformin primarily involves the inhibition of hepatic gluconeogenesis, leading to reduced hepatic glucose output, and it can also slow the absorption of glucose in the intestines.
Noticeable effects usually require 4 to 6 weeks of use.
The average decrease in HbA1c is about 0.6% to 1.4%.
Patients taking this medication often experience weight loss due to its impact on appetite.
Metformin should not be used in patients with kidney or liver disease, acute myocardial infarction, severe infections, or diabetic ketoacidosis.
Caution is advised when prescribing it to elderly patients over 80 years old, those with a history of congestive heart failure, or individuals with a history of alcohol abuse.
Long-term use of Metformin may interfere with vitamin B12 absorption.
Additionally, drug interactions can occur; for example, the effects of Metformin can be enhanced by Cimetidine, Furosemide, Nifedipine, and other medications.
5.
It is advisable for you to discuss these matters in detail with your family physician, especially regarding the use of medications, which should always be prescribed by a doctor.

Reply Date: 2016/03/26

More Info

Understanding Glycated Hemoglobin (HbA1c) is crucial for managing diabetes effectively. Your proactive approach to exercise and dietary control is commendable, especially given your family history of diabetes. Let’s address your questions one by one.

1. Fixed Time for Fasting Blood Sugar Tests: Yes, it is advisable to have your fasting blood sugar (FBS) tested at a consistent time each day, ideally after an overnight fast of at least 8 hours. Variations in your FBS readings can occur due to factors such as the time of day, your body’s natural circadian rhythms, and even the timing of your last meal. For the most accurate assessment, try to schedule your blood tests at the same time each day, preferably in the morning after waking up.

2. Fasting Blood Sugar Levels: Your fasting blood sugar levels ranging from 86 to 95 mg/dL are considered to be in the normal range, but they are on the higher end of the spectrum. According to the American Diabetes Association, a fasting blood sugar level of 100 to 125 mg/dL is classified as prediabetes. Therefore, while your levels are not yet in the prediabetic range, they are close, and it’s essential to maintain your healthy lifestyle to prevent progression.

3. Fluctuations in Glycated Hemoglobin (HbA1c): Your HbA1c levels between 5.0% and 5.2% are excellent and indicate good blood sugar control. The threshold of 5.7% to 6.4% is considered prediabetes, while 6.5% or higher indicates diabetes. Minor fluctuations in HbA1c can occur due to various factors, including changes in diet, physical activity, stress, and even laboratory variations. However, consistent readings above 5.2% should prompt further monitoring and possibly lifestyle adjustments. It’s important to remember that HbA1c reflects your average blood sugar levels over the past 2-3 months, so short-term changes are generally not a cause for concern unless they are consistently high.

4. Effectiveness of Metformin: Metformin is a first-line medication for type 2 diabetes and is effective in lowering blood sugar levels. Typically, you may start to see improvements in your blood sugar levels within a few days to a couple of weeks after starting Metformin. However, the full effect on HbA1c levels may take about 2 to 3 months to manifest. It’s important to combine medication with lifestyle changes, including diet and exercise, for optimal results.

In summary, maintaining a consistent schedule for blood tests, monitoring your fasting blood sugar levels, and understanding the implications of your HbA1c readings are all vital components of diabetes management. Continue your healthy lifestyle, and consider discussing your concerns with your healthcare provider, especially regarding the fluctuations in your HbA1c and the potential need for medication like Metformin. Regular follow-ups will help you stay on track and make necessary adjustments to your management plan.

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