Hi,
I test my blood sugar every day and I see some deviation among the readings: sometimes I get 97, sometimes 103, sometimes 107. It varies from reading to reading, so I’m not sure if those readings are normal or if I have high blood sugar.
Those readings were taken after I woke up in the morning before eating breakfast. The doctor is saying that my blood sugar is a little bit high but said that they don’t depend on that test and there is another test at the hospital called A1C.
Thank you very much.
Small differences such as 97, 103, and 107 mg/dL are expected. Glucose changes from day to day, and home meters also have normal measurement variation.
A reading of 97 mg/dL is within the normal fasting laboratory range. Results of 103 and 107 mg/dL fall within the laboratory prediabetes range of 100–125 mg/dL only if confirmed by an appropriate laboratory fasting plasma glucose test. A home glucose meter cannot diagnose prediabetes or diabetes.
Your doctor’s plan to obtain a laboratory HbA1c is reasonable. HbA1c below 5.7% is normal, 5.7–6.4% indicates prediabetes, and 6.5% or higher is in the diabetes range when appropriately confirmed.
Answer by Dr. Albana Greca, MD, MMedSc
Hello,
Your three numbers are close together and do not represent a dangerous fluctuation. A 10 mg/dL difference can result from biology, the meter, strips, and technique.
Even when meals and activity seem similar, morning glucose can be influenced by:
A carbohydrate-rich dinner may affect some readings but should not dismiss repeated fasting values above 100. See our fasting blood sugar guide.
Home meters are useful for monitoring but do not provide an exact laboratory value. Two tests minutes apart may differ.
Food residue, wet hands, insufficient blood, squeezing, damaged strips, temperature, and strip variation can change results.
Our home glucose testing guide describes common meter errors and how to repeat an unexpected result.
They suggest that laboratory testing is
Diagnosis requires a laboratory test. One borderline home result should not become a permanent label.
HbA1c estimates average glucose over approximately the previous three months and does not require fasting. The diagnostic ranges are:
HbA1c and fasting glucose may disagree, so the doctor may repeat the abnormal test or use another accepted test. See our HbA1c guide.
HbA1c can be affected by anemia, iron deficiency, recent bleeding or transfusion, altered red-cell survival, kidney or liver disease, pregnancy, and some hemoglobin variants. Tell your doctor if any of these apply or if HbA1c does not match your glucose readings.
Not everyone does. A 75-gram oral glucose tolerance test may help when fasting glucose and HbA1c disagree or when the clinician needs to evaluate how the body handles a standardized glucose drink.
Two-hour laboratory results are interpreted as below 140 mg/dL for normal, 140–199 mg/dL for prediabetes, and 200 mg/dL or higher for diabetes. A random plasma glucose test is mainly diagnostic when it is at least 200 mg/dL together with classic symptoms; it is not a standard test for diagnosing prediabetes.
The available tests are compared in our diabetes testing guide.
Without diagnosed diabetes or a clinician’s instruction, daily finger-sticks may add worry. A short log can help, but laboratory testing decides whether prediabetes is present.
Ask how often to test and when laboratory follow-up is needed.
Arrange earlier review if fasting readings repeatedly reach 126 mg/dL or higher, random readings reach 200 mg/dL or higher, or you develop unusual thirst, frequent urination, unexplained weight loss, blurry vision, recurrent infections, or marked fatigue.
Seek urgent care for very high glucose with vomiting, abdominal pain, rapid breathing, dehydration, confusion, or drowsiness.
Remember: readings of 97, 103, and 107 show mild variation, not a diagnosis. Laboratory HbA1c and fasting plasma glucose are the correct next steps.
Safety note: General education only. Home meter results cannot diagnose prediabetes or diabetes.
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