Blood glucose and ketone meters have become indispensable tools for individuals managing diabetes, adhering to the ketogenic diet, or simply aiming to enhance their metabolic health. While at-home meters may not match the precision of laboratory tests, their accuracy is sufficient for making informed decisions regarding glucose management. These devices are rigorously regulated by the FDA and other governing bodies to ensure their safety and effectiveness as medical devices. This article delves into the accuracy of keto-mojo devices, how they compare to lab tests, and how to ensure you get the most reliable readings.
Understanding Glucometer and Ketone Meter Accuracy
Accuracy Defined and Regulated by the FDA
In the United States and many other countries, over-the-counter glucose meters are classified as medical devices and must adhere to strict regulatory standards before they can be marketed. The FDA mandates that all blood glucose meters meet or exceed specific accuracy benchmarks to obtain 510k certification:
- 99% of all results must be within +/- 20% of a validated laboratory-based glucose measuring method
- 95% of all results must be within +/- 15% of a validated laboratory-based glucose measuring method
For instance, if a laboratory test indicates a blood glucose level of 100 milligrams per deciliter (mg/dL), a self-monitoring glucose meter must display results between 80-120 mg/dL for 99% of readings and between 85-115 mg/dL for 95% of readings from the same sample.
The FDA also requires manufacturers to demonstrate precision, which is the repeatability of results, across various glucose concentrations ranging from 30-400 mg/dL. This ensures that the meter performs consistently across the spectrum of possible results, from dangerously low to normal to dangerously high.
Manufacturers are obligated to test both meters and glucose strips for accuracy. They must also maintain an archive of strips in case any issues arise in the future. This rigorous testing and archiving process ensures that the glucometer and strips are safe and effective for monitoring blood glucose and making informed health decisions.
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While standalone blood ketone meters are not as strictly regulated as glucometers, combination glucose and ketone meters are held to higher standards than ketone meters. To ensure the most accurate blood ketone readings, it is advisable to opt for a 510k approved FDA-compliant glucose-ketone meter rather than a non-regulated meter that only measures ketone levels.
Home Meters vs. Lab Tests
While home glucose and ketone meters are accurate enough for making safe decisions, they are not as accurate as lab tests. Several factors contribute to this difference in accuracy.
Glucose meters use small blood samples obtained from a fingerstick, known as capillary blood. Capillary blood is more susceptible to metabolic influences than venous blood, which is drawn directly from a vein for lab tests. Venous blood provides a more representative measure of the body's circulating glucose levels and typically yields lower glucose levels than capillary blood.
The sample size also affects accuracy. Glucose strips typically hold less than one microliter of blood, whereas lab tests analyze blood samples around 0.5 milliliters, which is 500 times larger. Larger sample sizes generally lead to more reliable results.
Home equipment is also less sophisticated than lab equipment. Glucose meters cost approximately the same as an oil change for a car and report results in 5 seconds, while "gold standard" tests like gas chromatography-mass spectrometry (GCMS) use instruments costing between $80,000 and $400,000 and take at least 15 minutes to report results.
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Accuracy for Informed Decisions
Consumer-grade glucose meters may not rival the accuracy of lab-grade GCMS equipment, but they are accurate enough for their intended purposes.
The primary function of a glucose meter is risk management, which involves making acute care decisions regarding blood sugar levels. These decisions include detecting dangerously low or high glucose levels that require immediate attention and assessing the need for exogenous insulin to maintain healthy blood glucose levels.
Home glucose meters are accurate enough for:
- Tracking trends in glucose over time to measure metabolic health.
- Understanding the response to meals or specific foods by testing pre- and postprandial glucose.
- Calculating the glucose-ketone index (GKI) to ensure a state of therapeutic ketosis for managing medical conditions.
Furthermore, glucometers are portable and easy to use, unlike lab instruments, which require specialized personnel to operate.
Comparing Different Brands of Meters
Comparing results from different brands of meters is not a reliable way to assess accuracy. Some brands of glucose meters tend to provide lower results than lab results, even if they are still within the FDA's acceptable accuracy range. This can cause confusion when people switch between meters or compare results and assume that the higher reading must be inaccurate.
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Confirmation bias, the tendency to accept data that aligns with our preferences, can also play a role in how people interpret meter readings. However, it's important to remember that a meter that consistently reads lower than another is not necessarily more accurate or valid.
The most important factor is to stick with one trustworthy meter, make informed short-term glucose management decisions, and monitor metabolic health trends over time.
Avoiding Back-to-Back Readings
Taking back-to-back readings from the same glucose or glucose-ketone meter is not a reliable way to determine its accuracy. Variations in readings are expected due to the FDA's accuracy standards:
- +/- 15% variation compared to baseline lab results, 95% of the time
- +/- 20% variation compared to baseline lab results, 99% of the time
Performing back-to-back readings at home can further decrease accuracy due to:
- Prolonged exposure to air, which can oxidize glucose and skew readings.
- Rapid changes in blood glucose levels.
- Differences in glucose content from different fingers.
If you are concerned about the accuracy of your glucose meter, perform an accuracy test using a control solution.
Verifying Accuracy
If you suspect that your meter is providing incorrect readings or has been damaged, perform a control solution test. This test will confirm whether your meter is working correctly and meeting FDA accuracy standards.
Keto-Mojo meters come standard with glucose and ketone control solutions for testing meter accuracy. Before using the control solution, verify the expiration date, use properly stored and unexpired test strips, and only use Keto-Mojo control solutions with Keto-Mojo meters.
To perform the test:
- Prepare a glucose strip or ketone strip, or both.
- Gently shake the control solution before use.
- Place a drop of the control solution onto a clean, non-porous surface.
- Insert the strip into the meter and wait for the beep.
- Place the tip of the strip to the appropriate control solution and wait for your reading.
- Compare the meter reading to the ranges printed on your meter kit box or test strip box.
If your reading falls within the range, your meter is meeting the FDA standards of accuracy.
To perform a 5-strip test:
- Prepare 5 glucose strips or 5 ketone strips, or both.
- Gently shake the control solution before use.
- Place a drop of the control solution onto a clean, non-porous surface.
- Perform back-to-back tests with all 5 glucose or ketone strips using the single drop, noting each reading.
- Calculate the average of the 5 tests by adding up all of the readings, then divide the total by 5.
- Compare the average reading to the ranges printed on your meter kit box or test strip box.
If the reading average falls anywhere within the control range, your meter is accurate.
Common User Errors and Other Variables
Several factors can affect the accuracy of at-home glucose and ketone readings. These factors do not directly affect the accuracy or performance of your meter, but they can account for unexpected changes in your readings:
- Hydration status: Dehydration can raise blood glucose levels.
- Time of day: Glucose and ketone levels vary throughout the day.
- Protein consumption: High protein intake may temporarily reduce blood sugar.
- Exercise: Lower intensity aerobic exercise can temporarily lower blood glucose, while more intense anaerobic exercise can briefly raise it.
- Fasting or intermittent fasting: Can rapidly alter insulin sensitivity, affecting glucose levels.
- Psychological stress: Can increase glucose and ketone levels.
- "Hidden" carbs or other non-keto ingredients: Can increase blood sugar levels on the keto diet.
- Dietary supplements: Can raise or lower blood sugar, especially in people who take medications.
- Medication adjustments: Always speak to your doctor before adding a new supplement if you have a medical condition or take prescription medication.
- Taking exogenous ketones: As some people do for therapeutic purposes.
CGMs vs. Blood Meters: Making the Right Choice
Accuracy and Safety
As previously discussed, interstitial glucose readings from CGMs slightly lag behind actual blood glucose levels, making them less accurate than real-time blood glucose readings from a blood glucose meter. CGMs are also less accurate during episodes of hypoglycemia, which can increase the risk of harm.
CGMs do not measure blood ketone levels, so they are not helpful for detecting metabolic ketoacidosis.
A high-quality glucose-ketone meter is the clear winner for accuracy and safety. They are more accurate than any CGM and provide insight into ketone levels, which can alert users to ketoacidosis.
Keto Diet, Weight Loss, and Metabolic Health
For individuals following the keto diet for weight loss or metabolic health, a glucose-ketone monitor is more suitable than a CGM. CGMs do not provide blood ketone readings, making them less helpful for discovering trigger foods and exploring the interplay between glucose and ketone levels after meals.
Blood glucose-ketone meters have distinct advantages over CGMs for the ketogenic diet, weight loss, and metabolic health.
Diabetes Treatment Decisions
Most CGMs are not FDA-approved for making diabetes treatment decisions. Experts recommend confirming CGM readings using a finger stick glucometer or other FDA-indicated device for treatment decisions.
Keto-Mojo as a Tool for Monitoring Ketosis
The keto diet is a nutritional approach that restricts daily carbohydrate intake to induce a state of ketosis. The metabolic changes that characterize the KD reduce the dependence of athlete performance on limited carbohydrate stores and promote glycogen sparing during prolonged activity. Accurately monitoring BHB levels is important for maintaining diet adherence and making effective modifications to the diet. Desired metabolic adaptations to a ketogenic diet are made when the athlete is in a state of nutritional ketosis (NK) and BHB is increased above resting levels to at least 0.5 mM in the blood. Objective measurement of BHB levels is needed to confirm a state of NK, or to make necessary changes to the diet and activity level to achieve NK and resulting adaptations throughout the training cycle. Knowledge of blood glucose levels is also of interest when tracking metabolic adaptations, as glucose levels remain at normal physiological levels following ketogenic adaptation and are still used as substrate during exercise [18].
One of the most commonly used high-performing field measurement device is Abbott Labsâ Precision Xtra glucose/ketone monitor system (Meter 1). With daily utilization, this method may become expensive due to the cost of the disposable test strip needed with each measurement.
Keto-Mojo (Meter 2) is a relatively new measurement system that is considerably more affordable to use than Meter 1. For manufacturer-sold products, the cost of Meter 2 test strips for ketone and glucose testing are 1/5 and 1/6 the price of test strips for Meter 1, respectively. The reliability and practical value of Meter 2 must be assessed prior to use in healthy human populations. Therefore, one study objective was to evaluate the more affordable Meter 2 and compare it with Meter 1 to assess reliability and agreement for BHB and glucose measurement in healthy human subjects; and to assess the diagnostic performance of Meter 2 vs. Meter 1 for identifying NK at a level of BHB = 0.5 mM. Both Meter 1 and Meter 2 displayed excellent agreement between each other for ketone measurement.
Advantages of Keto-Mojo Monitors
Here are some benefits of using Keto-Mojo monitors:
- Bio-individuality: Keto Mojo takes bio-individuality into consideration, addressing the fact that bodies react differently. Frequent testing helps identify trigger foods or exercises that may disrupt ketosis.
- Digital Data Tracking: The Keto Mojo app seamlessly integrates with the monitor via Bluetooth, transferring data to a personal MyMojoHealth profile via the cloud.
- Glucose Ketone Index (GKI): Keto Mojo simplifies metabolic state assessment with the Glucose Ketone Index (GKI), calculated by dividing blood glucose level (mmol/L) by blood ketone level (mmol/L).
- Ease of Use: The monitor is user-friendly, requiring only the insertion of a ketone or blood glucose strip. A small blood sample is obtained via a finger prick using a lancet.