Can a multivitamin cause inaccurate glucose readings?

January 3, 2026 •

4 min read

According to the Centers for Disease Control and Prevention, over 38 million Americans have diabetes, relying on accurate glucose readings for management. A lesser-known fact is that certain ingredients found in a multivitamin can cause inaccurate glucose readings, potentially leading to misinformed health decisions. Understanding this interference is vital for anyone monitoring their blood sugar.

Quick Summary

Certain high-dose multivitamins, particularly those containing high levels of Vitamin C or Biotin, can interfere with glucose monitoring devices and lab tests. This interference can cause falsely high or low readings, depending on the supplement and the testing method. Awareness is key for anyone with diabetes to ensure accurate results.

Key Points

Vitamin C and Glucometers: High doses of Vitamin C can cause falsely elevated readings on some fingerstick glucose meters and CGMs by interfering with the electrochemical test strip.
Biotin and Lab Tests: High-dose Biotin supplements interfere with many lab immunoassays (e.g., thyroid tests), leading to false results, and should be paused before blood draws.
Device Dependency: Interference levels depend on the specific meter's technology, with some newer models having reduced susceptibility to interference.
Communication is Key: Always inform your healthcare provider about all supplements you take, including multivitamins and any high-dose formulas.
Proper Technique: Proper hand-washing, using unexpired strips, and correct storage are fundamental to avoiding inaccurate glucose readings.

Key culprits for inaccurate glucose readings

While a standard, balanced multivitamin is unlikely to cause issues, specific ingredients in high concentrations have been proven to interfere with glucose measurements. The two primary components to be aware of are Vitamin C (ascorbic acid) and Biotin (Vitamin B7).

High-dose Vitamin C (Ascorbic Acid) and glucose meters

High doses of Vitamin C can cause falsely elevated glucose readings on specific types of point-of-care (POC) glucose meters and continuous glucose monitors (CGMs). This interference is dependent on the testing technology used by the device. Many meters rely on an electrochemical method where a chemical reaction on a test strip creates an electrical current. Vitamin C, being an antioxidant, can participate in this reaction, generating a current that the meter misinterprets as glucose, resulting in a false positive.

Device-specific interference: Some older or specific meter models (like certain Roche and Abbott devices) are more susceptible to this interference. Newer models and those that use more advanced technology may have mechanisms to counteract this, but caution is always warranted with high doses.
CGM interference: Many CGMs, including Dexcom and Freestyle Libre, are also affected by high Vitamin C levels, with some manufacturers issuing specific warnings. Doses over 500 mg per day are often cited as a threshold for potential interference.
Intravenous vs. oral: Interference is most pronounced with very high intravenous doses of Vitamin C, such as those used in some cancer treatments. While oral multivitamins contain lower doses, megadoses or supplements specifically for immune support can still be a concern.

High-dose Biotin (Vitamin B7) and lab tests

Biotin, often marketed for hair, skin, and nail health, poses a different kind of risk. It doesn't typically interfere with fingerstick glucose meters. Instead, high-dose biotin supplements can significantly skew the results of many laboratory immunoassays, causing either falsely high or low results, depending on the test method. This can impact a wide range of tests, including those for thyroid function (TSH, T3, T4), troponin (for heart attacks), and certain hormone levels. While not a direct glucose meter issue, this is a critical concern for anyone undergoing comprehensive blood work to manage their diabetes and overall health.

Mechanism: Many lab assays use a biotin-streptavidin technology for detection. Excess biotin in a patient's blood can disrupt this binding process, leading to inaccurate results.
Dosage: Doses as high as 5,000 mcg to 10,000 mcg or more, often found in beauty supplements, are most problematic.
Recommendation: The FDA and labs like Quest Diagnostics advise patients taking high-dose biotin to stop supplementation for at least 72 hours before a blood draw to minimize interference.

Proper technique to avoid inaccurate readings

Besides supplement interference, many other factors can compromise the accuracy of your glucose readings. Following proper technique can help minimize errors and ensure reliable results.

Best practices for glucose monitoring

Wash and dry hands thoroughly: Any sugar residue from food or drink on your fingers can contaminate the blood sample and lead to a falsely high reading.
Use unexpired test strips: The enzymes on test strips have a limited shelf life and can degrade over time.
Store supplies correctly: Keep test strips in their original, tightly closed container away from heat, cold, and humidity.
Ensure proper blood sample size: Applying too much or too little blood can lead to inaccurate results or an error message.
Check for meter coding: If your meter requires coding, ensure the code on the meter matches the code on the test strip vial. Many modern meters are 'no-code'.
Consult your healthcare provider: Always inform your doctor about any supplements, medications, or high doses of vitamins you are taking, especially before blood work or testing.

Comparison of supplement interference


Feature	High-Dose Vitamin C	High-Dose Biotin
Affected Test Types	Point-of-care (fingerstick) glucose meters, some Continuous Glucose Monitors (CGMs)	Lab immunoassays (e.g., thyroid tests, troponin tests)
Effect on Readings	Primarily causes falsely high readings.	Causes falsely high or low readings depending on the specific lab test.
Recommended Action	Discuss potential interference with your doctor, especially with doses >500mg. Monitor readings carefully.	Stop taking supplements for at least 72 hours before lab blood draws.
Mechanism	Antioxidant interferes with the electrochemical reaction on the test strip.	Disrupts the biotin-streptavidin technology used in many lab assays.
Primary Concern	Misinterpreting blood sugar levels, potentially leading to incorrect insulin dosing.	Misdiagnosis of serious conditions like thyroid disorders or heart problems based on inaccurate lab results.

Conclusion

While multivitamins offer health benefits for many, the potential for high-dose ingredients like Vitamin C and Biotin to cause inaccurate glucose readings should not be underestimated. For those managing diabetes, reliable monitoring is non-negotiable. The key takeaway is awareness and communication. Always disclose your full supplement regimen to your healthcare provider. If you notice unusual or inconsistent readings after starting a multivitamin or a high-dose supplement, talk to your doctor immediately. Ensuring accuracy involves not only using the right technique but also understanding the potential impacts of dietary supplements on your specific testing devices and laboratory results.

For more information on lab test interference and biotin, refer to the FDA Safety Communication on Biotin Interference with Lab Tests.

Frequently Asked Questions

High doses of Vitamin C (ascorbic acid) can cause falsely high glucose meter readings, while high doses of Biotin (Vitamin B7) can interfere with lab test results, though not typically with fingerstick meters.

Many glucose meter and CGM manufacturers warn that doses of Vitamin C over 500 mg per day can potentially cause interference. Extremely high doses, such as those administered intravenously, cause significant, well-documented interference.

No, high-dose Biotin typically does not interfere with the immediate readings from a standard fingerstick glucose meter. Its main concern is with laboratory blood tests (immunoassays), which can lead to misdiagnoses for other conditions.

For individuals taking high doses of biotin, it is recommended to stop supplementation for at least 72 hours before a blood draw for laboratory tests.

Other supplements are less likely to cause immediate reading inaccuracies, though some, like Niacin (Vitamin B3) at high doses, can impact long-term blood sugar levels. Always consult a healthcare provider before taking new supplements if you have diabetes.

First, review your supplement labels for high doses of Vitamin C and Biotin. Ensure you are using proper testing technique (e.g., clean hands). If inconsistencies persist, consult your healthcare provider and consider temporarily pausing supplementation to see if readings stabilize.

The American Diabetes Association does not specifically recommend multivitamins for managing diabetes unless a specific deficiency is identified. A balanced diet is always the priority. Discuss any supplement use with your doctor to ensure it is appropriate for your health needs.