Regular blood sugar monitoring is a cornerstone of diabetes management. Understanding how, when, and why to test — and how to interpret the results — empowers patients to make real-time decisions about food, activity, and medication.

Methods of Blood Sugar Monitoring

Two main methods are available:

  • Self-monitoring of blood glucose (SMBG): Using a fingerstick blood sample and a glucose meter (glucometer). Provides an accurate reading at the moment of testing. Still useful for confirmatory testing when CGM readings are questionable.
  • Continuous glucose monitoring (CGM): A sensor worn on the skin that measures interstitial glucose every 1–5 minutes. Provides trend data, alerts, and downloadable reports. CGM has largely replaced fingerstick testing in Type 1 diabetes and is increasingly used in Type 2.

Understanding Your Glucose Numbers

Time PointTarget (Most Adults with Diabetes)
Fasting (before breakfast)80–130 mg/dL
Before meals80–130 mg/dL
1–2 hours after meals<180 mg/dL
Bedtime100–140 mg/dL
A1C (3-month average)<7% for most adults

What Is the A1C?

The A1C (hemoglobin A1c) test measures the percentage of hemoglobin in red blood cells that has glucose attached to it — a reflection of average blood sugar over the past 2–3 months. It is the primary benchmark for evaluating long-term diabetes control.

An A1C of 7% corresponds to an average glucose of about 154 mg/dL. Each 1% reduction in A1C reduces the risk of diabetes complications by approximately 35–40%.

A1C has limitations: it can be falsely high or low with certain blood conditions (hemolytic anemia, sickle cell, recent blood transfusion). In these situations, CGM time-in-range metrics are more reliable.

Hypoglycemia — Low Blood Sugar

Blood sugar below 70 mg/dL is considered hypoglycemia. Symptoms include shakiness, sweating, palpitations, irritability, confusion, and in severe cases, loss of consciousness. The "Rule of 15" for treating mild hypoglycemia:

  1. Take 15 grams of fast-acting carbohydrate (e.g., 4 oz juice, 3–4 glucose tablets, regular soda)
  2. Wait 15 minutes
  3. Recheck glucose — if still below 70, repeat
  4. Once glucose is above 70, have a snack containing protein if the next meal is more than 1 hour away

ðŸšĻ Severe Hypoglycemia: If you are unable to treat yourself due to confusion or unconsciousness, a family member or caregiver may need to administer emergency glucagon (Gvoke, Baqsimi nasal spray, or Zegalogue). Prescription glucagon kits or nasal glucagon should be available for anyone at risk of severe hypoglycemia.

Key Takeaways

  • CGM provides far more information than fingerstick monitoring alone
  • A1C reflects average glucose over 2–3 months — target is <7% for most adults
  • Pre-meal target is 80–130 mg/dL; post-meal target is <180 mg/dL
  • Treat mild hypoglycemia with 15g fast-acting carbs, recheck in 15 minutes
  • Emergency glucagon should be available for anyone at risk of severe low blood sugar
Medical Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before making any changes to your treatment plan. Individual medical decisions should be made in partnership with your physician based on your specific circumstances.