It's a very rough rule of thumb, take these numbers with a grain of salt. It could very well be that some food activates in 5 minutes etc. Different insulin typ

It's a very rough rule of thumb, take these numbers with a grain of salt. It could very well be that some food activates in 5 minutes etc. Different insulin types also have different curves. Anyways there are studies about the "inject 15min before food" approach: eg. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2945151/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2945151/