What does it mean when a pump is described as a "closed-loop" system?

A "closed-loop" or Automated Insulin Delivery (AID) system is an advanced setup where your Continuous Glucose Monitor (CGM) and your insulin pump directly communicate with each other using a smart algorithm. Instead of just delivering a steady, pre-programmed background rate of insulin, the pump automatically increases, decreases, or completely pauses your insulin delivery every few minutes based on the real-time readings from your CGM. This technology is fantastic for smoothing out blood sugar levels, preventing dangerous overnight lows, and automatically correcting highs. While it is not a cure and is considered a "hybrid" system—because you still have to manually interact with it for meals—it significantly reduces the heavy mental burden and constant math required to manage diabetes.