Regulators are warning that certain types of glucose monitoring sensors should no longer be used after manufacturer Abbott Diabetes Care reported that the devices have been linked to seven deaths and more than 700 injuries worldwide.

Some FreeStyle Libre 3 and FreeStyle Libre 3 Plus sensors may display falsely low glucose readings, the U.S. Food and Drug Administration (FDA) said this week. Persistently low readings can lead people with diabetes to make incorrect treatment decisions—such as consuming excessive carbohydrates or skipping or delaying insulin doses.

“Such decisions may pose a serious health risk, including possible injury or death,” the FDA warning states.

The sensors are devices that measure glucose levels in the fluid just beneath the skin, providing real-time blood sugar data, Euronews reports. Information from the sensor is transmitted wirelessly to a device or smartphone.

According to Abbott, the warning affects approximately three million sensors in the United States from a single production line. The company says about half of these devices have already been used or have expired.

Abbott’s FreeStyle Libre 3 was approved in Europe in 2020, and the sensors are available in Germany, Spain, Italy, France, the Netherlands, and the United Kingdom.

As of November 14, the company reported seven deaths worldwide and 736 serious adverse events.

Abbott has notified all customers about the issue. The company stated that it has identified and resolved the defect in the affected manufacturing batch.

According to the FDA, users should stop using the affected sensors and dispose of them properly.

The issue concerns FreeStyle Libre 3 sensors with model number 72080-01 and unique device identifiers 00357599818005 and 00357599819002. It also affects FreeStyle Libre 3 Plus sensors with model numbers 78768-01 and 78769-01 and unique device identifiers 00357599844011 and 00357599843014.