Hardware Specifications
A pump's ability to deliver micro-doses of insulin relies on its internal motor mechanism. While algorithms in closed-loop systems determine the dose, the hardware dictates the execution.
| Pump Model | Reservoir | Basal Increment | Form Factor |
|---|---|---|---|
| Tandem t:slim X2 | 300 U | 0.001 U/hr | Tubed (Micro-delivery) |
| Tandem Mobi | 200 U | 0.001 U/hr | Tubed (Wearable) |
| Omnipod 5 | 200 U | 0.05 U/hr | Patch (Tubeless) |
| Medtronic 780G | 300 U | 0.025 U/hr | Tubed (Syringe-drive) |
Infusion Sets: The Weak Link
The interface between the hardware and the human body remains the most common point of failure. Cannulas kink, tunnel, or cause inflammation.
- Teflon (90-degree): The standard. Easy insertion but prone to kinking on impact or in lean tissue. Recommended change: 2-3 days.
- Teflon (Angled): Inserted at 30-45 degrees. Better for low body fat or pediatrics.
- Steel (90-degree): Cannot kink. Ideal for users with frequent occlusions or allergies to Teflon. Must be changed every 2 days.
- Extended Wear: Medtronic's Extended set uses novel tubing materials to reduce insulin preservative degradation, allowing up to 7-day wear.
Insulin Degradation in Reservoirs
Plastic reservoirs and tubing interact with insulin over time, specifically binding to the preservatives (like cresol) and causing the insulin to polymerize or lose efficacy. Environmental factors like heat during travel or exercise accelerate this process. If you notice unexplained highs on day 3, it is often site degradation, not algorithm failure; check troubleshooting steps.
FAQ
- Why does my tubeless pump beep randomly?
- Piezoelectric buzzers in disposable pods fire on static discharge, occlusion detection, or expiration. A continuous tone indicates a fatal hardware fault requiring replacement.
- Can I use unapproved insulins?
- Most pumps are FDA-cleared only for Humalog and Novolog. Fiasp and Lyumjev (ultra-rapid) are known to cause higher rates of occlusions and site inflammation due to added niacinamide and citrate, though many use them off-label in DIY setups.