It sounds like the carbs you consumed didnt have a chance to start working before the insulin took effect. I would reduce the dose to 2iu next, just to be extra safe, as you learn how to control it. 30 min before taking your shot, eat a solid food meal containing a lean protein and 8oz sweet potato. You want to consume 10carbs per 1IU of insulin. 8 oz will be more than double that for 2iu. I would then take your shot along with 20g dextrose, BCAA and creatine. One hour later, I would have another solid food meal, containing protein and anouther 8 oz potato. 1 hour after that, have another 20g dextrose and BCAA shake. From there, you should be able to return to your normal meal schedule. When you move to 3iu, increase the dextrose to 30 grams. when you move to 4iu, increase the dextrose to 40g. If you go beyond 4iu, you may need to increase the carbs in the solid food meal.
Honestly, this is a little overkill on the carbs but if you have a very fast metabolism, which is the only time I suggest insulin, you should be fine, running this for 4 wks at a time.