Fasting Blood Sugar Levels: Causes and Concerns for Pre-Diabetes

Q: Fasting Blood Sugar Levels: Causes and Concerns for Pre-Diabetes

Hello： Based on your initial glycated hemoglobin (HbA1c) level of 6.5 and your relevant family history, you can be diagnosed with diabetes according to diabetes management guidelines. <br>However, diabetes patients are not completely unable to metabolize glucose; the body retains

Please consult a doctor regarding blood sugar issues. Thank you!

This year, at 42 years old, I have a standard build (166 cm / 55 kg) and a history of gallbladder removal surgery as well as kidney stones.
My father and grandmother have a history of diabetes.
In early January, a blood donation report indicated a hemoglobin A1c of 6.5.
Two weeks later, during a follow-up appointment, my hemoglobin A1c was measured at 5.7, and my estimated glomerular filtration rate (eGFR) was 71.063.
The doctor mentioned that I am in the prediabetic stage and do not require medication, suggesting a follow-up in six months.

After two months, I have managed to lose 4 kg through dietary control (reducing carbohydrates) and monitor my blood sugar three to four times a week.
Aside from one instance of a fasting blood sugar of 126 and a few post-meal readings between 146-160 after large dinners, my postprandial blood sugar levels have generally remained within normal ranges (fasting under 100, and post-meal two hours not exceeding 140).
However, this week I have consistently experienced abnormal fasting blood sugar levels (around 100-110), while my post-meal blood sugar remains normal (between 105-140).

Could you please explain why my fasting blood sugar is higher than my post-meal blood sugar on several occasions (with fasting blood sugar reaching 110 while post-meal is 105)? What could be causing this situation? Do I need to seek medical treatment or medication? Thank you very much!

Chen Feifei, 40~49 year old female. Ask Date: 2020/03/30

Dr. Lin Wuxuan reply Internal Medicine

Hello: Based on your initial glycated hemoglobin (HbA1c) level of 6.5 and your relevant family history, you can be diagnosed with diabetes according to diabetes management guidelines.
However, diabetes patients are not completely unable to metabolize glucose; the body retains varying degrees of glucose metabolism ability depending on the severity of the condition.
Your situation appears to be in the prediabetic stage, where you still have some capacity for glucose metabolism, which is why you may sometimes experience higher fasting blood glucose levels compared to postprandial levels.
For early-stage diabetes patients, the most important recommendation according to diabetes management guidelines is to focus on lifestyle modifications, including healthy eating, weight loss, and the establishment of exercise habits.
It is also advisable for you to consult with a metabolic specialist at a healthcare facility for regular monitoring of blood glucose and other related laboratory values.
If blood glucose levels are poorly controlled, after evaluation and discussion of a treatment plan with a specialist, medication may be considered based on the severity of the condition.

Reply Date: 2020/03/30

More Info

Understanding fasting blood sugar levels, especially in the context of pre-diabetes, is crucial for managing your health effectively. Based on your situation, it appears you are navigating the complexities of blood sugar regulation, particularly with a family history of diabetes and your recent test results indicating pre-diabetes.

Firstly, it’s important to understand the physiological mechanisms behind fasting blood sugar levels. Fasting blood sugar (FBS) is typically measured after an overnight fast of at least 8 hours. Normal fasting blood sugar levels range from 70 to 99 mg/dL. Levels between 100 and 125 mg/dL indicate pre-diabetes, while levels of 126 mg/dL or higher suggest diabetes. Your recent fasting blood sugar readings of 100-110 mg/dL place you in the pre-diabetic range, which aligns with your previous HbA1c results.

The phenomenon of having higher fasting blood sugar levels compared to postprandial (after meal) levels can be attributed to several factors:
1. Dawn Phenomenon: This is a natural increase in blood sugar that occurs in the early morning due to hormonal changes. Hormones such as cortisol, glucagon, and epinephrine increase insulin resistance, leading to elevated blood sugar levels upon waking. This could explain why your fasting blood sugar is higher than your post-meal readings.

2. Insulin Sensitivity: After eating, your body releases insulin to help cells absorb glucose. If your insulin sensitivity is good, your blood sugar will return to normal levels after meals. However, if your body is less sensitive to insulin in the morning, it may not effectively lower your fasting blood sugar.

3. Dietary Factors: Your dietary choices can also influence your blood sugar levels. A diet high in refined carbohydrates can lead to spikes in blood sugar, while a low-carb diet can help stabilize levels. Since you mentioned reducing carbohydrate intake, it’s possible that your body is still adjusting to these changes, which can affect fasting levels.

4. Stress and Sleep: Stress and poor sleep can also impact blood sugar levels. Cortisol, the stress hormone, can increase blood sugar levels, while inadequate sleep can affect insulin sensitivity.

Given your situation, it’s commendable that you have made dietary changes and are monitoring your blood sugar levels regularly. The fact that your postprandial levels are within normal ranges is a positive sign. However, the persistent higher fasting levels could indicate that further adjustments may be necessary.

Regarding medication, your doctor has advised against it for now, which suggests that they believe lifestyle modifications are sufficient at this stage. However, if your fasting blood sugar continues to rise or if you experience symptoms of hyperglycemia (such as increased thirst, frequent urination, or fatigue), it would be wise to consult your healthcare provider. They might consider further testing, such as an oral glucose tolerance test (OGTT), to assess your glucose metabolism more comprehensively.

In summary, while your fasting blood sugar levels are concerning, they are not uncommon for someone with pre-diabetes. Continue with your dietary management, maintain regular physical activity, and monitor your blood sugar levels. If you notice persistent abnormalities or have concerns, don’t hesitate to reach out to your healthcare provider for further evaluation and guidance. Regular follow-ups will be essential in managing your risk of progressing to diabetes.

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