Fasting Blood Sugar Always Above 100 mg/dL Causes

by Rony




Question from Rony:


My fasting blood sugar is always over 100 mg/dL, sometimes 102, 105, or 107. I lost almost 20 lb in one year, exercise 30 minutes daily, and eliminated sugar from my diet, but fasting glucose is still over 100. I also have anxiety and think too much. Could this be the cause?




Quick Answer


Rony, fasting blood sugar readings of 102–107 mg/dL are not diabetes, but they are slightly above the usual normal fasting range.


If these numbers are confirmed by a laboratory fasting glucose test, they fall in the prediabetes range. This does not mean you will definitely develop diabetes, but it is a useful early warning sign.


Anxiety, stress, poor sleep, late meals, hidden carbohydrates, insulin resistance, and the dawn phenomenon can all contribute to mildly high fasting glucose.



Answer by Dr. Albana Greca, MD, MMedSc


Dear Rony,


Your readings are not dangerously high, and they do not diagnose diabetes by themselves. But I would not call them completely normal either, especially if they are repeated fasting readings.


What Does Fasting Blood Sugar Above 100 Mean?


A fasting glucose test should be done after at least 8 hours without food or caloric drinks. In general:



  • Below 100 mg/dL is usually normal.

  • 100–125 mg/dL is usually prediabetes if confirmed.

  • 126 mg/dL or higher may suggest diabetes if confirmed.


So fasting readings such as 102, 105, and 107 mg/dL are mildly high. They deserve follow-up, but they are not an emergency.


Helpful page: normal fasting blood sugar levels.


Can Anxiety Raise Fasting Blood Sugar?


Yes. Anxiety and stress can raise glucose in some people because stress hormones tell the liver to release more glucose. Poor sleep can also make morning glucose higher.


However, anxiety should not be assumed to be the only cause. It is better to confirm your status with proper testing.


Other Common Causes



  • Dawn phenomenon, when the liver releases glucose early in the morning

  • Insulin resistance, especially with belly fat or family history

  • Late dinner or large evening carbohydrate portions

  • Poor sleep, sleep apnea, or high stress

  • Hidden carbohydrates from bread, rice, pasta, snacks, milk, fruit juice, or sweetened drinks

  • Some medicines, such as steroid medicines

  • Meter variation or testing before a full 8-hour fast


Helpful page: why is my blood sugar high in the morning?


Do Not Remove All Carbohydrates


You do not need to eliminate all sources of carbohydrate or “sugar.” Your body needs balanced nutrition. The goal is to avoid sugary drinks, sweets, and refined carbohydrates while choosing better carbohydrates in controlled portions.


Good choices may include vegetables, beans, lentils, oats, plain yogurt, whole fruits, and measured portions of whole grains.


Helpful resource: diabetes, carbs, and glycemic index.


What Tests Should You Ask For?


Ask your doctor for:



  • Repeat fasting plasma glucose from a laboratory

  • HbA1c

  • Oral glucose tolerance test if needed

  • Cholesterol and triglycerides

  • Blood pressure and waist measurement

  • Review of family history, sleep, stress, and medicines


Helpful page: blood tests for diabetes.


What Can You Do Now?



  • Keep exercising most days.

  • Add strength training 2–3 times weekly if your doctor says it is safe.

  • Avoid large late-night meals and large dinner carbohydrate portions.

  • Sleep regularly and reduce evening stress time.

  • Track fasting glucose for 1–2 weeks, but do not check obsessively.

  • Speak with your doctor if weight loss was unintentional or continues.



Important Safety Note


Seek medical care promptly if you have unexplained weight loss, extreme thirst, frequent urination, blurry vision, vomiting, dehydration, weakness, or blood sugar 200 mg/dL or higher with symptoms.




Doctor’s Note


Rony, your numbers are mildly high, not dangerous. Anxiety can contribute, but the best next step is confirmation with HbA1c and a repeat fasting lab test. Continue healthy habits, but avoid fear-based overchecking or extreme dieting.




Educational safety note: This answer is for general diabetes education only. It does not replace personal medical advice, diagnosis, or treatment. Do not start medicines, supplements, extreme diets, or exercise plans without speaking with your healthcare provider.



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Last reviewed: July 2026.


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