Why is it not recommended to aspirate Insulin injections? aren't insulin injections IM injections? and don't t?

Aspiration is the act of taking it in by breathing. This is NOT an efficient way of delivering insulin as it would be extremely difficult to ascertain just how much of a dose is actually utilised [utilized, if you are, in fact, one of my American cousins]. No, my friend, insulin injections are NOT IM (intramuscular). They are, in fact, subcutaneous, which means they are given into the fatty layers of tissue. This slows down the absorption rate of the insulin, as compared to intravenous insulin injections, which would only be done by medically qualified people.

When aspirated, the volume of insulin varies with pressure so you do not know how much insulin you're getting. Remember gases compress, Newtonian ideal liquids are uncompressible therefore a volume of liquid is a set amount but the same isn't true for a gas.