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 a

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.