Fasting Blood Sugar Variations: What You Need to Know

Fasting blood glucose

Hello doctor, I have a habit of regularly checking my blood sugar.
This morning, I went to the clinic and had my blood sugar tested, and the result was 124.
About three months ago, at the same clinic, it was in the 90s.
Then, about 10 minutes later, I went to another clinic and had it tested again, and this time it was 96.
Both tests were fasting tests.
Why is there such a large discrepancy? One test indicates normal levels while the other suggests I should start losing weight.
My lipid levels are all normal.

Cheng Cheng, 20~29 year old female. Ask Date: 2017/05/24

Dr. Xiao Yongxun reply Internal Medicine

Dear Mr.
Cheng,
1.
According to the diagnostic criteria for diabetes set by the American Diabetes Association: a.
A fasting plasma glucose level of ≥126 mg/dL after fasting for at least 8 hours, b.
A 2-hour plasma glucose level of ≥200 mg/dL during an oral glucose tolerance test, c.
A hemoglobin A1c (HbA1c) of ≥6.5% (this must be confirmed with a method that is certified by the National Glycohemoglobin Standardization Program (NGSP) and meets the standards of the Diabetes Control and Complications Trial (DCCT)).
The above conditions a, b, and c must be confirmed by two separate tests.
d.
If there are clinical symptoms of diabetes (such as polydipsia, polyuria, polyphagia, and weight loss), a plasma glucose level of ≥200 mg/dL is sufficient (this only needs to be confirmed once).
2.
The opinions of the physicians from both clinics should be acceptable.
Blood glucose levels can fluctuate; furthermore, capillary blood glucose levels obtained from finger pricks may differ from venous plasma glucose levels.
The interval between tests, along with factors such as exercise or other influences, can also cause variations in blood glucose levels; additionally, there may be discrepancies between different blood glucose meters.
This is why the American Diabetes Association and our country's diabetes associations have very strict regulations and requirements for diagnosing diabetes.
(Please note: "the above conditions a, b, and c must be confirmed by two separate tests.")
3.
If you have any questions, please consult with one of the physicians from those two clinics for follow-up and diagnosis.
It is not advisable to speculate or worry excessively on your own.
4.
Current research indicates that the risk factors for developing type 2 diabetes primarily include obesity, a family history of diabetes, lack of physical activity, a history of cardiovascular disease, gestational diabetes, giving birth to a baby weighing over 4 kg, polycystic ovary syndrome, acanthosis nigricans, dyslipidemia, and hypertension.
5.
Type 2 diabetes does not occur suddenly; it develops gradually due to factors such as obesity, poor dietary habits, lack of exercise, and unhealthy lifestyle choices.
Essentially, anyone with a family history of diabetes should consider early dietary and exercise interventions to control weight; this can help avoid the nightmare of diabetes.
6.
In terms of practical preventive measures, I personally recommend that you: chew your food thoroughly during meals, avoid overeating (aim for about 80% fullness), and limit the intake of high-calorie, high-fat, and high-sugar foods or beverages.
Reduce consumption of high-cholesterol and trans fats (often found in creamers, butter, ghee, instant coffee, milk tea, etc.) and high-fructose corn syrup (commonly found in commercial beverages, desserts, sodas, pastries, etc.).
These types of foods may be harder for the body to metabolize, may contain empty calories, and can lead to increased blood sugar levels.
Additionally, develop a regular exercise routine, such as playing sports, jogging, swimming, or cycling; in fact, taking a good walk for 30 to 60 minutes after each meal can be very effective.
In terms of lifestyle, avoid excessive stress and ensure adequate sleep; this will help reduce the secretion of related hyperglycemic hormones and increase the secretion of leptin, aiding in weight control.

Reply Date: 2017/05/24

More Info

Understanding fasting blood sugar variations can be quite complex, especially when you receive different results from different laboratories or testing sessions. Let's break down the factors that can contribute to these variations and what they mean for your health.

1. Understanding 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 are generally considered to be below 100 mg/dL. Levels between 100 and 125 mg/dL indicate prediabetes, while levels of 126 mg/dL or higher suggest diabetes. Given your recent results of 124 mg/dL and 96 mg/dL, it’s important to understand the implications.

2. Factors Influencing Blood Sugar Variations
Several factors can lead to discrepancies in fasting blood sugar readings:
- Testing Methodology: Different laboratories may use different testing methods or equipment, which can lead to variations in results. Even slight differences in calibration or technique can yield different readings.

- Timing of the Test: If there was any variation in the timing of your fasting period or the time of day when the blood was drawn, this could affect the results. Blood sugar levels can fluctuate throughout the day based on various factors, including meals, stress, and physical activity.

- Physiological Factors: Stress, illness, or even lack of sleep can influence blood sugar levels. For instance, if you were under stress or had not slept well before the test, this could lead to elevated blood sugar levels.

- Dietary Intake: The types of food you consume, particularly carbohydrates, can significantly impact your blood sugar levels. If you had a high-carb meal the night before or consumed alcohol, this could affect your fasting blood sugar.

3. Interpreting Your Results
Given your results of 124 mg/dL and 96 mg/dL, it’s essential to consider the context:
- 124 mg/dL: This reading is on the cusp of the prediabetes range. It suggests that you may need to monitor your blood sugar levels more closely and consider lifestyle changes, such as diet and exercise, to help manage your blood sugar.

- 96 mg/dL: This reading falls within the normal range. It indicates that your blood sugar levels are well-controlled at that time.

4. What Should You Do Next?
- Follow-Up Testing: It may be beneficial to have a follow-up test, ideally at the same laboratory, to confirm your fasting blood sugar levels. A hemoglobin A1c test can also provide a broader picture of your blood sugar control over the past 2-3 months.

- Lifestyle Modifications: If you are concerned about your blood sugar levels, consider adopting a balanced diet rich in whole grains, lean proteins, healthy fats, and plenty of fruits and vegetables. Regular physical activity is also crucial for maintaining healthy blood sugar levels.

- Consult Your Healthcare Provider: Discuss your results with your healthcare provider. They can help you interpret the results in the context of your overall health and may recommend further testing or lifestyle changes.

5. Conclusion
Blood sugar variations can be influenced by numerous factors, and it’s not uncommon to see different results from different tests. Understanding these variations is crucial for managing your health effectively. Regular monitoring, lifestyle adjustments, and consultations with your healthcare provider will help you maintain optimal blood sugar levels and reduce the risk of developing diabetes. If you have any further questions or concerns, don’t hesitate to reach out to your healthcare professional for personalized advice.

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