LO on the meter (below the measuring range)
The meter measured a blood glucose lower than the bottom of the range it can report, so it shows LO instead of a number. The makers read treat it as a possible very low level, not as a fault.
Check your meter’s manual — makers differ.
What it is for
Read what your own manual says and follow the plan your healthcare team gave you; the makers word it differently. OneTouch (LifeScan): “This may require immediate treatment according to your healthcare professional's recommendations. Although this result could be due to a test error, it is safer to treat first, then do another test.” Contour (Ascensia): “Contact your health care professional immediately.” Accu-Chek (Roche): “follow your healthcare professional’s instructions or contact your healthcare professional immediately.” FreeStyle (Abbott): with symptoms such as weakness, sweating, nervousness, headache or confusion, “follow your doctor’s recommendation to treat hypoglycaemia”; without symptoms, the FreeStyle booklet says to retest with a new test strip on your fingers.
These pages report what each maker’s manual says and quote it wherever health is involved. They do not diagnose anything, they are not medical advice, and they never tell you how to treat a result; only your own meter’s manual and your healthcare team can do that for your model.
- What it looks like
- The letters LO where the number would be, sometimes flashing with an arrow. The OneTouch Verio Reflect writes EXTREME LOW GLUCOSE and a Treat Low prompt instead.
- Names makers use
- LO (Accu-Chek, Contour, OneTouch Verio Flex, FreeStyle); EXTREME LOW GLUCOSE (OneTouch Verio Reflect)
Where makes differ
The floor is the same on every manual read, 20 mg/dL: the Accu-Chek Guide manual (Roche) says “lower than 20 mg/dL”, the Contour Next One guide (Ascensia) “under 20 mg/dL”, both OneTouch booklets (LifeScan) “less than 20 mg/dL”, and the FreeStyle Freedom Lite booklet (Abbott) “lower than 20 mg/dL (1.1 mmol/L)”. What they tell you to do first is not the same: the OneTouch booklets say to treat first and test again, the Contour guide says to contact your health care professional, and the FreeStyle booklet splits it by whether you have symptoms. The OneTouch Verio Reflect writes EXTREME LOW GLUCOSE instead of LO.
What it does not mean
LO does not mean the battery is low on the meters read here (they have a separate battery symbol), and it is not the same as LO.t on the OneTouch Verio Flex, which LifeScan’s booklet defines as the meter being too cold to test. A LO is not averaged: the FreeStyle booklet (Abbott) says it is stored as LO and “not included in your 7-, 14- and 30-day averages”.
Other symbols with the same shapes
Sources
No published standard we could check defines blood glucose meter control icons, so this meaning is taken from 4 makers’ own manuals and support pages, each fetched and read on the date shown:
- Roche: Accu-Chek Guide blood glucose meter — user manual (US, PDF) — Blood Glucose Warnings: “Blood glucose may be lower than the measuring range of the system”; Error Messages: “(lower than 20 mg/dL)”; “If your blood glucose result is displayed as LO or HI, follow your healthcare professional’s instructions or contact your healthcare professional immediately.” Checked 2026-09-28.
- Roche: Accu-Chek — Guide meter error codes (support pages for E-1 to E-14, HI, LO and the battery icon) — LO: “Blood glucose may be lower than the measuring range of the system. See the Unusual Blood Glucose Results section in the User Manual.” Checked 2026-09-28.
- LifeScan: OneTouch Verio Flex — owner’s booklet (US, PDF) — Caution, Low results: “shown as LO (meaning the result is less than 20 mg/dL), it may mean hypoglycemia … This may require immediate treatment according to your healthcare professional's recommendations … it is safer to treat first, then do another test.” Checked 2026-09-28.
- LifeScan: OneTouch Verio Reflect — owner’s booklet (US, PDF) — Troubleshooting: EXTREME LOW GLUCOSE, “Below 20 mg/dL”, Treat Low; “You may have a very low blood glucose level (severe hypoglycemia), below 20 mg/dL … Always treat according to your healthcare professional's recommendations.” Checked 2026-09-28.
- Ascensia: CONTOUR NEXT ONE blood glucose monitoring system — user guide (US, PDF) — Symbol table: LO “Blood glucose test result is below 20 mg/dL”; LO or HI Results: “your blood glucose reading is under 20 mg/dL. Contact your health care professional immediately.” Checked 2026-09-28.
- Abbott: FreeStyle Freedom Lite blood glucose monitoring system — owner’s booklet (Australia, ART22410-102 Rev. B, PDF) — LO and HI Readings: “If your test result is lower than 20 mg/dL (1.1 mmol/L), LO will appear … This reading indicates severe hypoglycaemia”; LO reading with and without symptoms; LO stored in memory and not included in averages. Checked 2026-09-28.
Written in our own words; quotations are the makers’ wording.