Whenever I prime my insulin pen, different amounts come out. I always set it to 1 unit, and press in. Sometimes only 1 drop comes out, sometimes a stream comes out. How do i know this doesn't happen during the actual injection? I am really frustrated because this is confusing me. How do I know that when Im injecting say 5 units, it doesn't really give me 6 or 7? Do the amount of units that go in have anything to do with how hard you press? I am using Humalog and was just recently diagnosed.

The needle on the pen holds some insulin. The goal of the prime is to fill the empty space in the pen with insulin, and get old insulin stuck in the needle from leakage or previous uses out of the needle. So, we you are getting more insulin out of the prime, it probably means there was some insulin already in the needle. When you are getting less on the prime, it probably means that there was little to no insulin in the needle already. The goal of priming is to get rid of the variances so you actually get the correct dose when you actually take your shot.