Common Mistakes to Avoid When Testing Your Blood Sugar
05 Sep 2025 David A. Galbreath, M.D.
Common Mistakes to Avoid When Testing Your Blood Sugar
Managing diabetes often requires regular blood sugar testing. This routine can provide essential information about how your body responds to food, exercise, medication, and stress. However, errors in technique or interpretation can lead to inaccurate readings and potentially affect your diabetes management plan. This article delves into common pitfalls people encounter when testing their blood sugar and offers practical advice on how to avoid them, ensuring accurate and reliable results.
Neglecting to Wash and Dry Your Hands
The Problem
One of the most pervasive mistakes is failing to wash and dry hands thoroughly before testing blood sugar. Residual food, lotions, dirt, or even traces of sugar can contaminate the sample, leading to falsely elevated blood glucose readings. This is especially crucial as everyday substances may contain sugars or compounds that interfere with the testing process.
Why It Matters
Inaccurate readings can lead to unnecessary medication adjustments or dietary changes based on flawed information. Over time, consistently incorrect data can lead to poor glycemic control, potentially increasing the risk of diabetes-related complications. Fasting Blood Glucose What Your Morning Numbers Are Telling You
How to Avoid It
- Wash Hands Thoroughly: Use warm water and soap to wash your hands for at least 20 seconds.
- Rinse Well: Ensure all soap residue is removed, as some soaps contain moisturizing agents that could affect the reading.
- Dry Completely: Use a clean, lint-free towel to dry your hands. Dampness can dilute the blood sample and alter results.
- Alcohol Swabs: If soap and water aren't available, use an alcohol swab. However, ensure the alcohol evaporates completely before lancing your finger, as residual alcohol can also skew the reading.
Incorrect Lancing Technique
The Problem
The way you lance your finger can significantly impact the quality and quantity of the blood sample. Common errors include lancing the fingertip, not applying enough pressure to draw blood, or repeatedly squeezing the finger too forcefully.

Why It Matters
Lancing the fingertip is more painful because of the higher concentration of nerve endings in this area. Insufficient blood volume forces one to excessively squeeze the finger, which can dilute the blood with interstitial fluid, resulting in an inaccurate, often lower, reading.
How to Avoid It
- Choose the Right Spot: Lance the side of your fingertip, slightly off-center. This area is less sensitive and provides adequate blood flow.
- Use the Correct Lancing Device Setting: Adjust the depth setting on your lancing device according to your skin thickness. Start with a lower setting and increase gradually until you obtain an adequate blood drop.
- Proper Lancing Technique: Hold the lancing device firmly against your finger and press the release button. Avoid pressing too hard, as this can cause bruising.
- Encourage Blood Flow Gently: After lancing, gently lower your hand and massage your finger towards the puncture site to encourage a sufficient blood drop to form. Avoid forceful squeezing.
Using Expired or Damaged Test Strips
The Problem
Blood glucose test strips contain chemicals that react with glucose in the blood to produce a reading. These chemicals degrade over time, particularly when exposed to air, moisture, or extreme temperatures. Using expired or damaged test strips can lead to unreliable results.
Why It Matters
Expired test strips may produce falsely low readings, causing a person to believe their blood sugar is under control when it is not. This can delay necessary treatment and increase the risk of hyperglycemic episodes.
How to Avoid It
- Check Expiration Dates: Always check the expiration date on the test strip vial before using any strip. Dispose of expired strips properly.
- Proper Storage: Store test strips in their original, tightly sealed vial in a cool, dry place, away from direct sunlight and humidity.
- Avoid Contamination: Do not touch the test strip at the area where the blood sample is applied.
- Look for Damage: Inspect test strips for any visible damage or discoloration before use. Discard any strips that appear compromised.
Table: Guidelines for Test Strip Storage
| Condition | Recommendation | | ------------------ | --------------------------------------------------------------- | | Temperature | Store at recommended temperature (usually between 36°F and 86°F) | | Humidity | Keep away from moisture; store in a dry location | | Light Exposure | Avoid direct sunlight | | Container | Always store in the original, tightly sealed vial | | Expiration Date | Use before the expiration date printed on the vial |
Improper Meter Maintenance and Calibration
The Problem
Blood glucose meters, like any precision instrument, require regular maintenance and calibration to ensure accurate readings. Dust, dirt, and variations in temperature and humidity can affect the meter's performance.
Why It Matters
An uncalibrated or poorly maintained meter can produce readings that deviate significantly from actual blood sugar levels, leading to incorrect treatment decisions.
How to Avoid It
- Regular Cleaning: Clean the meter regularly with a soft, dry cloth. Avoid using water or solvents, unless specified by the manufacturer.
- Calibration: Follow the manufacturer's instructions for calibrating the meter. Some meters require manual calibration with a control solution, while others calibrate automatically with each test strip.
- Control Solutions: Use control solutions to verify the accuracy of the meter and test strips. Perform this test periodically, especially when opening a new vial of test strips or if you suspect the meter is not functioning correctly.
- Battery Check: Ensure the meter has sufficient battery power. Low battery can lead to inaccurate readings. Replace the batteries as needed.
- Update Software: If your meter uses software, ensure it is updated to the latest version to maintain optimal performance.
Inconsistent Timing and Logging of Readings
The Problem
Blood sugar levels fluctuate throughout the day in response to food intake, physical activity, medication, and stress. Inconsistent timing of tests and failure to log readings accurately can make it difficult to identify patterns and trends in blood sugar control. The Ultimate Fasting Blood Glucose Guide Preparation Ranges And Results
Why It Matters
Without a clear understanding of how your blood sugar varies at different times, it's challenging to make informed decisions about diet, exercise, and medication adjustments. Incomplete or inaccurate records hinder effective diabetes management.
How to Avoid It
- Establish a Testing Schedule: Work with your healthcare provider to establish a testing schedule that aligns with your treatment goals. Common testing times include before meals, two hours after meals, and at bedtime.
- Consistent Timing: Try to test your blood sugar at the same time each day. This helps minimize variability due to diurnal rhythms.
- Accurate Logging: Record your blood sugar readings immediately after testing, along with relevant information such as the time of the test, food intake, physical activity, medication dosages, and any unusual circumstances (e.g., illness, stress).
- Use a Logbook or App: Use a physical logbook or a diabetes management app to track your readings and other relevant information. These tools can help you visualize trends and identify areas for improvement.
- Share Data with Your Healthcare Provider: Bring your logbook or app data to your healthcare appointments so your provider can review your readings and make informed recommendations.
Example of Blood Sugar Log
| Date | Time | Blood Sugar (mg/dL) | Food Intake | Activity | Medication | Notes | | ---------- | ------ | ------------------- | -------------------------- | -------------------- | ---------------------- | ----------------------------- | | 2024-07-14 | 7:00 AM | 110 | N/A | N/A | 10 units of insulin | Fasting | | 2024-07-14 | 9:00 AM | 160 | Oatmeal with berries | Light walking | N/A | Post-breakfast | | 2024-07-14 | 12:00 PM| 120 | Salad with grilled chicken | N/A | N/A | Pre-lunch | | 2024-07-14 | 2:00 PM | 145 | N/A | N/A | N/A | Post-lunch | | 2024-07-14 | 6:00 PM | 105 | N/A | N/A | N/A | Pre-dinner | | 2024-07-14 | 8:00 PM | 130 | Salmon with vegetables | N/A | N/A | Post-dinner | | 2024-07-14 | 10:00 PM| 115 | N/A | N/A | N/A | Bedtime |
Ignoring Meter Error Messages
The Problem
Blood glucose meters are designed to display error messages when they detect a problem with the testing process. Ignoring these messages and continuing to test without addressing the underlying issue can lead to inaccurate results and potentially mask serious malfunctions.
Why It Matters
Error messages indicate that something is interfering with the meter's ability to accurately measure blood glucose. Ignoring these warnings can result in consistently flawed readings and jeopardize your diabetes management.
How to Avoid It
- Read the Manual: Familiarize yourself with the error messages specific to your meter model. The user manual provides detailed explanations and troubleshooting steps.
- Address the Problem: When an error message appears, stop testing and follow the recommended troubleshooting steps. This may involve replacing the test strip, cleaning the meter, or checking the battery.
- Contact Customer Support: If you cannot resolve the issue, contact the meter manufacturer's customer support line for assistance.
- Replace Faulty Equipment: If the meter continues to display error messages despite troubleshooting, consider replacing the meter.
Conclusion
Testing blood sugar accurately is a cornerstone of effective diabetes management. By avoiding these common mistakes – such as neglecting hand hygiene, using improper lancing techniques, using expired test strips, neglecting meter maintenance, inconsistent timing, and ignoring error messages – individuals can ensure their blood glucose readings are reliable and contribute to informed treatment decisions. Regular and accurate monitoring, coupled with collaboration with healthcare providers, is crucial for achieving optimal glycemic control and minimizing the long-term complications of diabetes. What Is A Normal Blood Sugar Level The Definitive Chart For 2024
References and Further Reading
- common mistakes when trying to control blood sugar and how to fix them yoPTyJ
- how to manage blood sugar a beginner s guide to glucose control 1wmCcj
- the blood sugar diet 21 friendly meals to stabilize your levels ddsqYe
- are your blood glucose levels normal the definitive guide Rl8XoK
- a1c to blood sugar conversion chart how to use the eag calculator G0O50K