How to Reset a Glucose Meter: Date, Memory & Codes

Diabetes

Most home glucose meters don’t have a reset button. “Resetting” usually means one of four things: removing and replacing the battery to clear an error, setting the correct date and time in the setup menu, switching units (mmol/L or mg/dL), or deleting stored results. The exact button sequence depends on your meter, so use the manual or the manufacturer’s helpline, and don’t erase readings your diabetes team may want to see.

By Dr. Ema HudsonUpdated: October 20263 min read

The short answer

Frozen or stuck on an error: remove the battery for about a minute, replace it, then set date and time if prompted.
Wrong date or time: enter setup mode (often by holding the main or “M” button with the meter off) and step through the settings.
Wrong units: many meters have fixed units; if yours shows mg/dL instead of mmol/L (or vice versa), contact the manufacturer for a replacement.

What “reset” can mean

Goal	Usual method	Notes
Clear a frozen screen or repeated fault	Battery out for 30–60 seconds, then back in	Stored results usually survive; date/time may need re-entering
Correct date and time	Setup menu via button hold (see manual)	Important: wrong times scramble averages and app uploads
Change units mmol/L ↔ mg/dL	Often impossible by design; some meters allow it in setup	Units are locked in many countries to avoid mistakes
Delete memory	Setup option on some meters; on others not possible	Download or photograph results first
Coding (older meters)	Enter or insert the code that matches the strip vial	Most modern meters are “no coding”
Factory reset	Rarely available to users	Call the helpline

Changing the battery

Low batteries cause odd behaviour, blank screens and errors. Most meters use one or two CR2032 or CR2025 coin cells, or AAA batteries; the type is printed inside the battery cover. After changing the battery, check the date and time. If the meter keeps showing a fault after a fresh battery and fresh strips, run a control-solution test and call the manufacturer.

Before you delete stored readings

Upload them to the manufacturer’s app or software, or photograph the logbook screen.
Bring them to your diabetes appointments; patterns matter more than single numbers.
Remember that some readings may be wrong (for example from a washed-out strip). Mark them in the app rather than deleting.
If a meter is shared (it shouldn’t be), deleting readings won’t fix mixed data; each person needs their own meter.

Checking the meter is working: control solution

Control solution is a liquid with a known glucose range, printed on the strip vial. Run a control test when you open a new box of strips, after dropping the meter, if results don’t match how you feel, or after a reset. If the result falls outside the printed range twice, don’t rely on the meter. Error codes and accuracy are explained in glucose meter error codes and in the diabetes care guide.

Frequently asked questions

How do I reset a ReliOn Prime meter?

ReliOn meters (sold by Walmart) have a setup mode for date, time and units; the button sequence is in the owner’s booklet and on ReliOn’s support pages. For persistent faults, call the toll-free number on the back of the meter.

Do I need to calibrate my meter?

Modern meters calibrate automatically with each strip (“no coding”). Older meters needed a code entered to match each vial of strips. Some continuous glucose monitors need fingerstick calibration; follow their instructions.

My meter shows a time from years ago. Does it matter?

Yes, if you use averages, apps or share data with your clinic. Set the correct date and time in setup; the readings themselves are not affected.

More on this topic: accurate testing and meter errors are covered in Diabetes Care: Glucose Meters, Diabetes Medicines and GLP-1 Pens.

Sources and further reading