Coach Trevor from enhanced athlete talks about this in youtube videos about small frequent shots of slin/gh throughout the day is very beneficial.
It can be good with low or even no carbs but you would have to be careful. Taking it before fasted cardio with synthetine is great. There is also merit in low dosed slin throughout the day with your standard meals in regards to muscle building. I experimented for a short time with that approach and did get fuller but also tigther at the same time. I actually just posted a fairly long post on Anasci about this subject (someone asked about slin and fatloss) so will copy and paste it here as it sort of matches with this thread...
It can help with fat loss but you have to be careful. Personally I think it's a waste of time using slin alone for fat loss but that doesn't mean using insulin in general is a waste. The one method someone could try would be just one dose first thing in the morning before fasted cardio. I am talking about 3iu Humulin-r and have carbs on you just incase but that dose should be fine. I would recommend adding Synthetine to this stack as the insulin shuttles the l-carnitine into the muscle cells and this will be amazing for fat burning. You could do the same before weight training too and believe me it does make a difference.
Personally I wouldn't recommend frequent insulin at high doses through the day for most on here. It's simply not needed. Fact is insulin will likely make many fatter as they eat too much on it (use it with a typical bulking diet). Slin will lower the utilization of fat for energy over time (unless used with Synthetine). It also inhibits lipase which breaks down fat tissue so slows fat burning when used frequently. I am not saying someone very lean could use slin like CG has and get some good weight from it as I have done it myself and many others over the years. The added fullness alone if you stay around the same bodyfat will be an illusion in itself.
Now if someone was on an effective aas cycle and following a good diet you could use slin to blow up but get lean at the same time. It's a great tool for this but I would recommend using it at specific times... basically around training and with carbs and other aids such as glutamine, creatine, l-carnitine etc. Insulin increases glucose transportation both in fat and muscle cells. Therefore many need to be careful when adding it in at random times unless they are very lean and well pretty much have a furnace for a metabolism from effective training and dieting over time (and of course genetics).
So use it when active and lifting weights with lot's of muscle building ingredients (oral aas, aminos, carbs, creatine etc) and drive all of those nutrients into the working muscles. Then for the rest of the day follow a relatively low carb diet to keep insulin levels low and of course increase insulin sensitivity for your next shot. I think this is the best general approach for growing and getting lean using insulin but there are 101 other ways that could work. Just don't think your average 230 pound 13% bf guy on here will blow up with lean tissue if using 100iu slin pre day with high carbs as it's not going to happen for most.