3 ms·

The difference is the pancreas reacts immediately to changes and has no practical delay for its effects, same concept as PID controllers in engineering.

by epilys 3y ago

danbruc 3y ago
So the limiting factor is the subcutane delivery, i.e. if the insulin could be delivered into the blood stream, then continuous glucose monitoring and controlled precise insulin doses could work as well as the pancreas?
- mlsu 3y ago
  The subcutaneous part is not really solvable, but even if it were, "real" insulin is much faster than even the fastest insulins (lispros) that we currently have. So there is a delay between delivery and action. There is also a delay on the sensing side; the pancreas always knows what's up, but even cutting edge CGM technology has significant delays, mostly related to that subcutaneous issue from my understanding.
  - haldujai 3y ago
    There are faster acting insulins creatively named "faster aspart" and "ultra rapid lispro" with the latter beginning to appear in the bloodstream at 2 minutes and reaching 50% effect around 20 minutes. With that said the difference between CGM/pumps and the human body's mechanisms of blood glucose regulation is not purely due to pharmacokinetics, regulation of blood sugar is very complex and we still don't fully understand them but there are multiple hormones and factors affecting blood glucose regulation. As one example some incretins are released in response to ingested food content and stimulate insulin secretion before blood glucose levels rise. We can't replicate that just by measuring blood glucose (not that we necessarily have to). The homeostatic mechanisms of the human body are fascinatingly complex.
- rrrrrrrrrrrryan 3y ago
  It's a huge oversimplification, but essentially yes. The current external artificial pancreas solutions operate subcutaneously, and your pancreas gets to work more directly with your blood. Subcutaneous blood sugar readings lag about 20 minutes compared to actual blood (finger pricks), and subcutaneous insulin delivery lags behind a healthy pancreas by even longer.

The difference is the pancreas reacts immediately to changes and has no practical delay for its effects, same concept as PID controllers in engineering.

by epilys 3y ago

The difference is the pancreas reacts immediately to changes and has no practical delay for its effects, same concept as PID controllers in engineering.

danbruc 3y ago

So the limiting factor is the subcutane delivery, i.e. if the insulin could be delivered into the blood stream, then continuous glucose monitoring and controlled precise insulin doses could work as well as the pancreas?

mlsu 3y ago
The subcutaneous part is not really solvable, but even if it were, "real" insulin is much faster than even the fastest insulins (lispros) that we currently have. So there is a delay between delivery and action. There is also a delay on the sensing side; the pancreas always knows what's up, but even cutting edge CGM technology has significant delays, mostly related to that subcutaneous issue from my understanding.
- haldujai 3y ago
  There are faster acting insulins creatively named "faster aspart" and "ultra rapid lispro" with the latter beginning to appear in the bloodstream at 2 minutes and reaching 50% effect around 20 minutes. With that said the difference between CGM/pumps and the human body's mechanisms of blood glucose regulation is not purely due to pharmacokinetics, regulation of blood sugar is very complex and we still don't fully understand them but there are multiple hormones and factors affecting blood glucose regulation. As one example some incretins are released in response to ingested food content and stimulate insulin secretion before blood glucose levels rise. We can't replicate that just by measuring blood glucose (not that we necessarily have to). The homeostatic mechanisms of the human body are fascinatingly complex.
rrrrrrrrrrrryan 3y ago
It's a huge oversimplification, but essentially yes. The current external artificial pancreas solutions operate subcutaneously, and your pancreas gets to work more directly with your blood. Subcutaneous blood sugar readings lag about 20 minutes compared to actual blood (finger pricks), and subcutaneous insulin delivery lags behind a healthy pancreas by even longer.