The warning is device-specific
The manufacturer warns that more than 500 mg of vitamin C per day may affect Libre 3 Sensor readings. For the Libre 3 Plus Sensor, its warning concerns more than 1,000 mg daily and explicitly describes falsely elevated readings. [1]
A falsely high result can conceal a severe low-glucose event. These are interference thresholds in device labeling, not recommended supplement amounts or general vitamin C safety limits. [1]
Distinguish a measurement problem from a metabolic change
The warning does not mean vitamin C necessarily raised the person’s true glucose. It means the sensor result may be distorted under the stated conditions. Different devices and models can have different interference characteristics. [1]
Check the exact sensor’s current instructions and the vitamin C total from supplements and other products. If readings do not fit symptoms or an interference warning applies, follow the device’s confirmation instructions and the diabetes-care plan rather than making a medication adjustment from a potentially misleading value. [1]
Read the full model name
Imagine two sensors share a brand but have different model names. A vitamin C threshold copied from one manual should not automatically be applied to the other.
| Detail | Interpretation |
|---|---|
| Libre 3 | Warning above 500 mg/day |
| Libre 3 Plus | Warning above 1,000 mg/day |
| Falsely high reading | Not proof of true glucose rise |
Sources for this article
- Important Safety Information | FreeStyle Libre Providers
Source consulted: 2026-09-19. This is a reference resource, not a claim that we conducted the studies or tested a product.