Blood Test Results: Impact of Fasting on Diabetes Diagnosis

Q: Blood Test Results: Impact of Fasting on Diabetes Diagnosis

Dear Mr. Zhang： 1. Your questions should be discussed with your primary care physician, as there are many factors that need to be considered. 2. According to the American Diabetes Association's diagnostic criteria for diabetes： a. Fasting plasma glucose leve

Please ask your questions regarding blood tests?

Hello, doctor.
Last November (2023), I experienced some health issues.
Starting around June 2023, I noticed increased appetite, thirst, and urination, but my weight did not decrease.
I went to the hospital for a consultation and had blood tests done.
I had my last meal at 12:30 PM that day, and when I went for my appointment in the evening, the doctor mentioned that I needed to fast for the blood test.
Due to time constraints, I had my blood drawn at 7 PM that same day.
The test results indicated that my blood glucose level was too high, at 143 mg/dL.
I would like to know if this result could be affected by my insufficient fasting time, and whether this blood glucose level is accurate.
Given the timing, I did not truly fast for 8 hours before the blood draw, and based on this number, the doctor diagnosed me with type 2 diabetes and started me on medication for management.
Additionally, during my company health check in March 2022, my fasting blood glucose level was measured at 120 mg/dL, which is considered prediabetes.
Is it possible for diabetes to progress so rapidly within a year, or do I still fall into the prediabetes category? Although I am currently on medication, there have been a few occasions when I forgot to take my medication in the morning due to rushing out, and my blood glucose levels before and after meals have remained within the normal range.
I have also been controlling my diet and exercising regularly.
Could it be that I have reversed my diabetes? Since I am still taking medication, I am unsure whether my blood glucose levels are normal due to the medication or if they have improved on their own.
I apologize for the many questions, and I appreciate your response in advance!

Mr. Zhang, 40~49 year old female. Ask Date: 2024/01/30

Dr. Xiao Yongxun reply Family Medicine

Dear Mr.
Zhang:
1.
Your questions should be discussed with your primary care physician, as there are many factors that need to be considered.
2.
According to the American Diabetes Association's diagnostic criteria for diabetes: a.
Fasting plasma glucose level ≥ 126 mg/dL after fasting for more than 8 hours, b.
Plasma glucose level ≥ 200 mg/dL during a 2-hour oral glucose tolerance test, c.
HbA1c ≥ 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)), and the above a, b, c criteria must be met on two separate occasions.
d.
Clinical symptoms of diabetes (such as polyuria, polydipsia, polyphagia, and unexplained weight loss) with any plasma glucose level ≥ 200 mg/dL (this can be confirmed with just one test).
3.
The onset of diabetes is mostly not sudden but rather progressive.
Clinically, in addition to fasting blood glucose, postprandial blood glucose, glycated hemoglobin, and even lipid levels should also be considered.
4.
Medications for chronic diseases are often taken once or twice a day.
When the concentration in the blood reaches a stable level, even if you occasionally eat less, the residual medication in the body will still have an effect, thus blood glucose and blood pressure will not suddenly become uncontrolled.
5.
Dietary control for diabetes includes eating until 80% full, avoiding eating too quickly or overeating, and avoiding high-sugar, high-fat, and high-calorie foods or beverages.
It is advisable to avoid three-in-one coffee, two-in-one coffee, cakes, and fried foods; dinner should not be too heavy, and moderate activity should be done after meals before going to bed.
Regular exercise is equally important, aiming for at least three times a week, with each session lasting about an hour; otherwise, at the very least, a walk after meals should be taken to avoid sitting down to work immediately.
Additionally, ensuring adequate sleep and reducing life stress will also help in blood glucose control.

Reply Date: 2024/01/30

More Info

Understanding blood test results, particularly in the context of diabetes diagnosis, requires careful consideration of several factors, including fasting duration, previous test results, and lifestyle changes. In your case, the situation is multifaceted, and I will address each aspect to provide clarity.

Firstly, regarding your blood test results, you mentioned that your blood sugar level was recorded at 143 mg/dL after a fasting period that was less than the recommended 8 hours. According to the American Diabetes Association (ADA), a fasting blood glucose level of 126 mg/dL or higher is indicative of diabetes. Since your test was conducted after only about 6.5 hours of fasting, it is possible that this could have influenced your results. Generally, shorter fasting periods can lead to inaccurate readings, potentially resulting in higher blood sugar levels than what might be observed with a full 8-hour fast. Therefore, while the reading of 143 mg/dL is concerning, it may not be entirely conclusive without a proper fasting period.

In addition to your recent test, you mentioned a previous fasting blood glucose level of 120 mg/dL, which falls into the prediabetes category (100-125 mg/dL). The progression from prediabetes to diabetes can indeed occur relatively quickly, especially if there are underlying risk factors such as obesity, sedentary lifestyle, or genetic predisposition. However, it is also important to note that diabetes is typically a progressive condition, and fluctuations in blood sugar levels can occur based on various factors, including diet, exercise, stress, and medication adherence.

You also raised a valid concern about whether your lifestyle changes, including diet control and regular exercise, might have led to improvements in your blood sugar levels. It is indeed possible to manage and even reverse prediabetes or type 2 diabetes through lifestyle modifications. Regular physical activity and a balanced diet can significantly enhance insulin sensitivity and help regulate blood sugar levels. However, it is crucial to monitor your blood sugar levels consistently, especially if you occasionally forget to take your medication. The fact that you have recorded normal blood sugar levels on days when you did not take your medication suggests that your lifestyle changes may be having a positive effect, but it does not necessarily mean you have reversed your diabetes.
To accurately assess your current status, it would be beneficial to have a follow-up appointment with your healthcare provider. They may recommend additional testing, such as an HbA1c test, which provides an average blood sugar level over the past 2-3 months. This can help determine if your blood sugar levels are consistently within a normal range or if further intervention is necessary.

In conclusion, while your recent blood sugar reading is concerning, the accuracy of that reading may be influenced by the insufficient fasting period. The progression from prediabetes to diabetes can happen, but it is also manageable with lifestyle changes. Regular monitoring and consultation with your healthcare provider will be essential in navigating your diabetes management effectively. Remember, diabetes management is a continuous journey, and staying informed and proactive about your health is key.

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