High Fasting Blood Sugar: Is It Prediabetes?

High fasting blood sugar?

Hello Dr.
Lee, I am currently 25 years old, weighing 50 kg with a height of 167 cm.
In mid-September, I underwent a company-arranged health check at a clinic in Japan.
The test results showed a fasting blood glucose level of 111 mg/dL (after fasting for six hours), which was diagnosed as abnormal.
Does this mean I am in the prediabetes stage? The health check was conducted at 2 PM, and I had eaten two pieces of cake and a cup of milk (approximately 350 ml) at 8 AM that morning (six hours before the test).
After eating, I took a nap until noon.
Would this affect the accuracy of the test results? Thank you.

W, 20~29 year old female. Ask Date: 2020/09/27

Dr. Li Jian reply Internal Medicine

The standard fasting test requires an 8-hour fasting period.
It is recommended to repeat the test; if the result is still above 100 mg/dL, then a hemoglobin A1C test should be conducted for further diagnosis.

Reply Date: 2020/09/27

More Info

Hello! Thank you for your question regarding your fasting blood sugar levels and the potential implications for prediabetes. Based on the information you provided, let's break down your situation and clarify what your results might mean.

Firstly, a fasting blood sugar level of 111 mg/dL is indeed considered abnormal. According to the American Diabetes Association (ADA), normal fasting blood glucose levels are below 100 mg/dL. A fasting blood sugar level between 100 and 125 mg/dL is classified as "impaired fasting glucose," which is often referred to as prediabetes. If your fasting blood sugar level is 126 mg/dL or higher on two separate tests, it would indicate diabetes.

Now, regarding the context of your test: you mentioned that you had consumed two pieces of cake and a glass of milk about six hours prior to your blood test. While fasting typically means no caloric intake for at least eight hours, consuming high-sugar foods like cake can significantly impact your blood sugar levels. However, since you did not eat for six hours before the test, your blood sugar level could still reflect the effects of your earlier meal, especially if it was high in carbohydrates.
In your case, the combination of a relatively short fasting period and the consumption of sugary foods could have contributed to the elevated fasting blood sugar level. It’s essential to ensure that you are fasting for the appropriate duration before testing to get an accurate reading. For future tests, aim for at least an eight-hour fast, and try to avoid high-sugar foods the night before.

Given your age (25 years) and the fact that you are at a healthy weight (167 cm and 50 kg), it’s also worth considering other factors that could influence your blood sugar levels, such as stress, sleep quality, and physical activity. If you are experiencing high levels of stress or not getting enough sleep, these factors can also lead to elevated blood sugar levels.

To summarize, while your fasting blood sugar level of 111 mg/dL does suggest that you may be in the prediabetes range, it’s crucial to consider the context of your test. I recommend that you follow up with your healthcare provider for further evaluation. They may suggest repeating the fasting blood glucose test after a proper fasting period or conducting an HbA1c test, which provides an average blood sugar level over the past two to three months.
In the meantime, maintaining a balanced diet, engaging in regular physical activity, and monitoring your blood sugar levels can help you manage your health effectively. If you have a family history of diabetes, it’s especially important to stay vigilant about your lifestyle choices and health screenings.

If you have any further questions or concerns, please don’t hesitate to reach out to your healthcare provider for personalized advice and support.

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