Insulin syringes are incredibly small. They do leave a puncture mark but you need a magnifying glass to see them.
In regular course of injections the smalled needle used is a TB needle. It does leave a distinct mark.
Regular insulin is an old time brand for rapid acting.
It used to be that Lilly Regular and NPH was all that was available.
Now there are probably 15 different brands out there.
Just think rapid acting insulin.
When I inject this evening I'm taking a magnifying glass to look! I wonder where Michael found the "Regular" insulin. Thanks for the reply.