Elevated Fasting Blood Sugar: Causes and Concerns

Fasting blood glucose levels are elevated?

On October 14, 2021, I went to the emergency room due to discomfort from vaccine side effects, around 8 PM after dinner, feeling very anxious (due to chest pain).
The emergency department recorded a blood glucose level of 171.
A few days later, on October 18, I visited a clinic for another blood glucose test, which showed a fasting blood glucose level of 83 and a hemoglobin A1c of 5.5.
The clinic physician mentioned that blood sugar can also rise under stress and anxiety.

On November 27, I visited the cardiology department at the hospital, where my fasting blood glucose was recorded at 85.
On January 9, 2022, I was diagnosed with bacterial acute gastroenteritis, having developed a fever and diarrhea since Saturday, and I was unable to sleep all night due to diarrhea.
I went to the emergency room early Sunday morning (after having eaten plain rice porridge for breakfast), where my blood glucose was measured at 191.
However, the emergency physician did not comment on the blood sugar level, only prescribing antibiotics and medications for fever and gastrointestinal issues.
On December 10, 2021, a laboratory test showed a fasting blood glucose level of 103, and an additional hemoglobin A1c test was also conducted, which remained at 5.5.
On December 13, I visited the hospital to inquire about my blood sugar levels.
The physician indicated that levels below 110 are not a major concern, but after discussing my medical history and family history (with diabetes in my grandmother and aunt), he suggested that an Oral Glucose Tolerance Test (OGTT) would be more prudent (I have not yet scheduled the OGTT).
I would like to ask the physician if having a fasting blood glucose level below 110 is acceptable.
Many sources indicate that levels above 100 should be monitored, while others suggest that levels above 100 but below 110 are normal, depending on the testing method.
My hemoglobin A1c has consistently remained at 5.5, which is within the normal range.
Should I be concerned? Currently, I have started to exercise (after being diagnosed in September and injuring my toe in November, I had not exercised for about three months) and adjusted my diet.
Additionally, I have a history of anxiety disorder.
If I experience a day without sleep, my anxiety tends to escalate.
I have medication at home (Mirtazapine 15 mg), and if I cannot sleep for 2-3 days, I take half a tablet (7.5 mg).
Will this medication affect my blood sugar levels?

Niming, 20~29 year old female. Ask Date: 2022/12/13

Dr. Li Jian reply Internal Medicine

Fasting blood glucose greater than 100 mg/dL or hemoglobin A1c greater than 5.6% indicates prediabetes.
Low-dose mirtazapine is not commonly associated with hyperglycemia.
Maintaining proper dietary control and lifestyle adjustments is key.
Thank you for your inquiry.

Reply Date: 2022/12/13

More Info

Elevated fasting blood sugar levels can be concerning, especially when there is a family history of diabetes. Your situation, where you have experienced fluctuations in blood sugar levels due to various stressors and health conditions, raises several important points to consider.

Firstly, it is essential to understand that blood sugar levels can be influenced by numerous factors, including stress, illness, and dietary habits. In your case, the elevated blood sugar readings of 171 and 191 during periods of acute stress (such as heart pain and gastrointestinal illness) are not uncommon. Stress can trigger the release of hormones like cortisol and adrenaline, which can increase blood sugar levels. This phenomenon is often referred to as "stress-induced hyperglycemia."
Your subsequent readings of 83 and 103 mg/dL, along with a stable HbA1c of 5.5%, indicate that your average blood sugar levels are within the normal range. The American Diabetes Association defines normal fasting blood sugar levels as less than 100 mg/dL, with levels between 100 and 125 mg/dL considered "prediabetes." Therefore, your fasting blood sugar levels below 110 mg/dL are generally not a cause for concern, especially given your consistent HbA1c levels.

However, the spike to 191 mg/dL is noteworthy and warrants further investigation. The Oral Glucose Tolerance Test (OGTT) that your doctor suggested is a valuable tool for assessing how your body handles glucose over time. It can help determine if you have impaired glucose tolerance or diabetes, especially given your family history.

Regarding your anxiety and the use of Mirtazapine, it is important to note that some medications can influence blood sugar levels. Mirtazapine, an antidepressant, has been associated with weight gain and changes in metabolism, which could potentially affect blood sugar control. However, the impact varies among individuals. If you find that your blood sugar levels are consistently elevated after starting the medication, it would be prudent to discuss this with your healthcare provider.

In summary, while your fasting blood sugar levels below 110 mg/dL are generally acceptable, the occasional spikes during periods of stress or illness should be monitored. Maintaining a healthy lifestyle through regular exercise and a balanced diet is crucial, especially given your family history of diabetes. It’s also essential to manage your anxiety, as chronic stress can have long-term effects on your overall health, including blood sugar regulation. Regular follow-ups with your healthcare provider and monitoring your blood sugar levels will help ensure that any potential issues are addressed promptly.

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