Pump Occlusions and Site Failures
The majority of unexplained hyperglycemia in pump therapy stems from the infusion site, not the algorithm. The subcutaneous tissue reacts to the foreign body (cannula) and the chemical preservatives in the insulin (cresol/phenol).
| Symptom | Technical Cause | Resolution |
|---|---|---|
| High BG, zero IOB, no ketones | Kinked Teflon cannula | Replace with Steel cannula (pumps specs) |
| High BG after day 2 | Site inflammation/tunneling | Change site, rotate using our tool |
| Repeated "Occlusion" Alarms | Motor back-pressure exceeded | Clear tubing, check for crystallization |
CGM Sensor Drift and Noise
CGM sensors are electrochemical wires. "Noise" (jagged graphs) indicates the sensor is struggling to measure the current accurately. This happens due to dehydration, pressure on the sensor (compression lows), or immune response encapsulating the wire.
- Compression Lows: Lying on the sensor pushes interstitial fluid away from the filament, causing a false drop. Check if the reading jumps back up instantly upon waking.
- Day 1 Jumpiness: The trauma of insertion causes localized inflammation, making initial readings erratic. Consider "soaking" the sensor by inserting it 12 hours before activating it.
Algorithm Lockouts
Systems like Control-IQ will lock out automatic correction boluses if you manually bolus, or if you hit the max daily limit. If you are stuck at 250 mg/dL and the algorithm is only increasing basal, the most effective technical override is an injection via smart pen or syringe to break the resistance, then entering that dose manually into the pump to prevent stacking.
FAQ
- Why does insulin leak around my site?
- This is "tunneling." The pressure of the bolus exceeds the tissue's absorption rate, forcing insulin back up the outside of the cannula. Switch to longer cannulas or multi-wave boluses.
- My CGM fell off. Can I glue it?
- Use medical adhesives like Skin Tac or Mastisol before insertion. If it's peeling, apply an overpatch (Opsite Flexifix or GrifGrips).