An artificial pancreas is a medical technology system that helps people with diabetes keep blood glucose closer to a safe range. It does not replace the entire pancreas, but it automates part of the job of insulin regulation. The system combines a continuous glucose monitor, a control algorithm, and an insulin pump into a closed loop.
This matters because stable glucose levels reduce the risk of short-term emergencies and long-term complications.
Key Facts
- Closed-loop control means sensor data is used to automatically adjust insulin delivery.
- Main parts: continuous glucose monitor, control algorithm, insulin pump, and patient.
- Glucose concentration is often measured in mg/dL or mmol/L.
- Time in range commonly refers to the percent of time glucose is about 70 to 180 mg/dL.
- Correction dose estimate: insulin needed = (current glucose - target glucose) / correction factor.
- Carbohydrate meal dose estimate: insulin needed = grams of carbohydrate / insulin-to-carb ratio.
Vocabulary
- Artificial pancreas
- A device system that automatically adjusts insulin delivery using glucose sensor data and a control algorithm.
- Continuous glucose monitor
- A sensor that measures glucose in tissue fluid every few minutes and sends readings to a receiver or pump.
- Control algorithm
- A set of computer instructions that decides how much insulin to deliver based on glucose trends and targets.
- Insulin pump
- A wearable device that delivers rapid-acting insulin through a small tube or patch cannula.
- Closed-loop system
- A feedback system in which measurements are used to adjust the system output automatically.
Common Mistakes to Avoid
- Thinking an artificial pancreas cures diabetes, which is wrong because the system manages insulin delivery but does not restore normal pancreatic cell function.
- Ignoring sensor delay, which is wrong because continuous glucose monitors measure tissue fluid glucose that can lag behind blood glucose during rapid changes.
- Assuming the pump gives insulin instantly with immediate effect, which is wrong because rapid-acting insulin still takes time to absorb and lower glucose.
- Forgetting meal information, which is wrong because many systems still need carbohydrate announcements to handle the fast glucose rise after eating.
Practice Questions
- 1 A person's glucose is 220 mg/dL, the target is 110 mg/dL, and the correction factor is 50 mg/dL per unit of insulin. What correction dose does the algorithm estimate?
- 2 A meal contains 75 g of carbohydrate and the insulin-to-carb ratio is 1 unit per 15 g. How many units of insulin are estimated for the meal?
- 3 Explain why a closed-loop artificial pancreas may reduce insulin delivery when glucose is falling, even if the current glucose reading is still above the target.