I have never had any problems with it, I take 10 i.u. 15 minutes before I finish training and then when I finish I drink a 1000 calorie shake loaded with sugars, these two should peak at the same time if done like this. Then I just eat as normal for the rest of the day. I think as long as you are regularly getting in plenty of complex carbs then a little insulin after training does no harm. I am really considering staying on while I am off gear for a few months as I have continued to gain for the past few weeks of being off and am now up to 230 lbs and staying fairly lean.