What to do if…
your glucose monitor or insulin device alarms and you are not sure what it means

What to do now

1. Check how you feel first. If you have signs of a hypo (shaky, sweaty, confused, blurred vision, sudden weakness), treat it as low blood sugar right now.
2. If possible, do a finger-prick blood glucose check now. Treat lows based on the finger-prick result and symptoms, not a sensor you don’t trust.
3. If your blood glucose is low (commonly below 4.0 mmol/L) or you feel low: take 15–20g fast-acting sugar, wait 10–15 minutes, then recheck. Repeat if still low. When you’re back up and stable, have a longer-acting carb snack/meal if your next meal isn’t soon (follow your personal plan).
4. If someone is unconscious, having a seizure, or can’t swallow safely: call 999. If you have a prescribed emergency glucagon kit and someone present knows how to use it, use it while waiting for help.
5. Look at the alarm message and sort it into one quick bucket (no deep decoding):
   • Low / urgent low → treat as above.
   • High → confirm with finger-prick; if you feel unwell, think about ketones (next step).
   • Delivery problem / occlusion / no delivery / pump stopped → assume insulin may not be getting in.
   • Sensor error / signal loss / calibration needed / app disconnected → assume the reading may be unreliable.
   • Low reservoir / low battery / “change set/sensor soon” → fix once you’ve confirmed you’re safe.
6. If you suspect insulin delivery failed (pump alarm): act as if insulin might be interrupted.
   • Check for obvious issues: pump suspended/stopped, kinked tubing, dislodged or painful site, wet/leaking adhesive, empty reservoir/cartridge, expired insulin.
   • If you can, change the infusion set/cannula and insulin.
   • Use your backup plan (many people are told to use insulin pens for correction and basal cover if the pump is unreliable). If you don’t have a clear plan, call NHS 111 or your diabetes team’s urgent line rather than guessing doses.
7. If glucose is high and you feel unwell, or you use a pump and think insulin may have been interrupted: if you have ketone strips/meter, check ketones.
   • Call 999 or go to A&E now if you have symptoms that could be DKA (for example vomiting, severe abdominal pain, fast/deep breathing, fruity-smelling breath, unusual drowsiness/confusion) or your ketones are high on your meter/strips.
   • If you’re not sure but feel worse or can’t keep fluids down, get urgent medical advice via NHS 111.
8. If the alarm comes through a phone/app: quickly check the basics so you don’t miss the next alert—phone not on silent, volume up, “Do Not Disturb” off (or exceptions set), app notifications allowed, Bluetooth connected, battery saver not blocking alerts. Then re-check the device screen to confirm the alarm state.
9. Make it safer for the next hour. Tell someone nearby (or call someone) what’s happening; keep fast-acting sugar, your meter/strips, and ketone supplies with you; recheck often until you feel steady and readings make sense.