The State of Commercial AID
Automated Insulin Delivery (AID), or closed-loop, systems rely on PID (Proportional-Integral-Derivative) controllers or Model Predictive Control (MPC) to adjust insulin delivery based on CGM inputs. Unlike DIY Looping, commercial systems prioritize safety (preventing hypoglycemia) over aggressive correction.
| System | Algorithm Type | Target BG | Auto-Bolus Limit |
|---|---|---|---|
| Tandem Control-IQ | PID (Zone-MPC) | 112-160 mg/dL | 60% of correction, 1/hr |
| Omnipod 5 | MPC | 110, 120, 130, 140, 150 | Micro-boluses every 5m |
| Medtronic SmartGuard | PID | 100, 110, 120 | Dynamic based on IOB |
| CamAPS FX | Adaptive MPC | 104 (adjustable) | Fully adaptive |
Algorithm Logic Breakdown
Tandem Control-IQ
Uses a fixed basal profile as a baseline. It predicts glucose 30 minutes into the future. If predicted >160 mg/dL, it increases basal. If predicted >180 mg/dL, it delivers an automatic correction bolus (60% of calculated need, max once per hour). If predicted <112.5 mg/dL, basal suspends. It relies heavily on user-programmed settings (Basal, ISF, Carb Ratio). For exercise, the target shifts to 140-160 mg/dL.
Omnipod 5
Uses Model Predictive Control based on Total Daily Insulin (TDI). It ignores user-programmed basal rates in auto mode, instead dynamically adapting micro-boluses every 5 minutes to guide glucose to the target. This adaptive nature means it takes 2-3 pod changes to "learn" user needs, requiring patience and data analysis.
CamAPS FX
A self-learning algorithm developed at Cambridge. It is arguably the most advanced commercial system, particularly approved for pregnancy and pediatrics (age 1+). It continuously adapts basal delivery and correction logic based on diurnal variations and insulin sensitivity shifts.
Limitations of Current Systems
Commercial AIDs are limited by insulin pharmacokinetics. Rapid-acting insulin takes 15-20 minutes to begin working and peaks at 60-90 minutes. Algorithms cannot compensate for rapid carbohydrate absorption without user-initiated bolusing. Use our calculators to ensure your underlying settings are solid.
FAQ
- Why am I stuck high on Control-IQ?
- The 60% correction bolus limit and 1-hour lockout can lead to prolonged highs if the initial meal bolus was missed. See troubleshooting for manual override strategies.
- Does Omnipod 5 learn my carb ratios?
- No. It only learns basal needs (TDI). You must still fine-tune your Carb Ratio and ISF for mealtime boluses.