Initially I tried to hide it, would go to the bathroom to inject insulin if in a restaurant. After a few times though I found this was more disruptive than just doing it at the table, and let's face it public bathrooms are not the cleanest of places. It's amazing how many people don't notice at all. Generally if people do notice and take an interest they just want to ask a few questions, I've not really had any bad reactions - my friends who have issues with needles tend to just look the other way.