Well I can't devote the time to put this eloquently or back things up scientifically, but think of the way that type II diabetes is developed. It's because people don't eat properly and their bodies stop releasing insulin efficiently and appropriately. I personally think by introducing exogenous insulin during the pre-diabetes stage you may give the pancreas a chance to relax. Especially considering that bodybuilders spike insulin quite often or during a critical time such as post-workout. This is undoubtedly taxing on the body for many reasons. So if you introduce exogenous insulin then that's one less stress on the body.
Even if this does not improve insulin sensitivity and appropriation, I think that at the very least it's neutral and not something that'll actually INDUCE diabetes. Perhaps if you use insulin at huge doses haphazardly you could somehow retard your body's response to glucose and impair things.. but I don't think so. Like you said, there probably isn't much scientific research and we all know that things on paper are much different in real life, especially if we consider the doses, dosing protocols and eccentric conditions a bodybuilder's body is in (heavily muscled, crazy conditioning, tons of eccentric drugs and exogenous hormones, etc). We are pioneers in this field and anecdotal feedback and empirical data is critical.
I used a BSL monitor for about a year before I really tried slin. I used USPLabs religiously and I believe that even a supplement was able to change my insulin sensitivity and body composition in a positive way. When I tried slin extensively I learned many things too. I haven't used it consistently enough to see large gains though. I basically just use it if I train really hard and beat my body down consecutive days in a row. If I lose weight and need to fill back up again I'll use it twice a day and then the next day or two.
It's debatable to what sort of degree, but you can acquire some visceral fat too which is a concern. My insulin sensitivity is great though. For years I abstained from sugar and simple carbs while bulking up. I went from 100lbs to 165-170lbs, tried some failed oral experiments and dropped muscle and put on fat. After yo-yo dieting inconsistency and indecisively (didn't know if I wanted to bulk or cut) I finally became pretty heavily muscled and conditioned and began using real AAS. I failed with that too but have a very respectable physique and started experimenting with slin, GH and thyroid meds so I feel that I'm quite cognizant. I now eat sugar, white rice like a mother fucker, pizza, junk food, whatever. And as long as it's done within some sort of limitation I still feel that my body responds to macronutrients very favorably. If I augment my diet for optimal performance I can put on much more muscle and get myself much more conditioned than ever before. When I use something like slin it propels this even further.
I think to capitalize on the benefits of insulin you need to use some thyroid so fat gains aren't as MUCH of a concern and GH will also bring things to a new level. I'm assuming that anyone using slin is on a very good amount of AAS too, otherwise your efforts are futile. If you're off AAS then I think slin, T3 and GH are good to keep a certain degree of muscle and conditioning but it'll certainly not put a lot of new mass on, it'll just keep you from shrinking and keep you full and relatively tight if your diet's on point.
In any event, I suppose that's my two cents. I'm sure others can relate. Perhaps digress or even correct me where I'm wrong. I know my body quite well being a stoner and an ex-heavy psychonaught (no more tripping, just weed now). And having a struggle from a Thai Lady boy physique to one that is not huge, but turns every head in the gym, is something that gives me a bit of credibility I'd say. A lot of the information out there is nothing but bro science but I've read as many medical texts as I could having a mother who's a nurse and family members who are doctors. I also used to scour PubMed in a quest for size but I feel that I have enough knowledge in the gym and in the kitchen to get where I want. If anyone wants to talk more about slin I'll start reading up again and try to dedicate some time to put in some decent bullshitting. I hope that we can get my niccas tbombz and vanb up in this. They're very knowledgeable dudes and can politely correct anywhere that I'm mistaken and add some serious fuel to this discussion.
