Truth be told, I took insulin on occasion for durations of less than 4 weeks and usually never exceeded 10iu per day. I primarily ran humulin R, I would say about 4 or 5 runs total in my 20's, again durations of less than 4 wks total and rarely used it more than once a year. I used humalog maybe twice during that time.
I ran HGH 2-3x at the most during that time period. I had experience using insulin with the HGH as well as insulin solo, which is why I'm saying that solo was more fat gain than anything now looking back on it.
I run lantus and nolvalog pens now, since I'm prescribed them. I use about 36iu per day of the lantus (24 hr insulin) and I would say on average of 60 units a day of nolvalog, but if I'm eating pretty tight and lowering carbs I can get away with about 30iu a day of nolvalog.
There are so many things concerning glucose that ppl aren't aware of, for example often times WITHOUT any carbs it can get more elevated since the liver dumps sugar into the bloodstream as a survival mechanism. Also, those workouts first thing in the a.m. on an empty stomach can jack your glucose up since the liver especially likes to dump the sugar in that scenario too. Fats can slow down carbohydrate digestion and elevate sugar as well. Something like a ribeye steak with no carbs at all can jack my sugar up to hell and back. It's very tricky, you learn what works and what doesn't over time. For myself, the best thing to control my glucose is a carb controlled diet with proper insulin to accomadate it, but NOT a carb deprived diet. If I keep it under 40 grams of carbs per meal I can usually stay about 5iu per shot of insulin. The average human releases about 50iu per day of insulin naturally I think.
So think of exogenous insulin in a similar way to natural amounts. You eat like shit , you need more insulin and hence store more fat. If someone not on insulin eats like shit they'll produce more insulin and store more fat.