Years ago when first testing out a nutritional ketogenic diet, I did a bit of research into other diets, including radically different (or even opposite) ones, like the Starch Diet.
Interestingly, among the various diets I found a lot of similar, sometimes essentially the same arguments in favor of them and reported outcomes (historical/evolutionary arguments, people now not dying of diseases, etc). All seemed to agree on a few things, but particularly that the middle ground Standard American Diet seemed to be just terrible one way or the other.
I just ended up finding the science, evidence and arguments for the ketogenic diet more convincing, and also felt it was an easier route to avoiding sugar anyway (which at that time I was convinced was a problem more than I was convinced of anything else), since then, a lot more evidence has pointed to the flaws of the other findings and support a ketogenic diet, but I’ll admit I haven’t kept as up to date on the research and arguments in favor of other diets.
I do still hold the impression though that there are multiple ways to properly construct a diet that may be radically different and still all yield pretty good results, at least for some amount of time (there is evidence of over time certain ones having various unexpected disadvantages for some people, like weakening of bones, for instance). But, the rules seem to shift depending on what you are working with.
The understanding of Insulin relating to Type 2 Diabetes seems pretty solid to me though, as does reducing carbs to reduce insulin. However, even with a high carb diet I’d speculate some may reduce insulin, or improve the use of insulin, by eating ‘better carbs’ perhaps (rice has a lot less fructose and other problems than, say, wheat, for instance) or otherwise setting an environment where perhaps the body is more efficiently moving everything through the system (a raw potato diet where that is the only thing someone eats, for instance, as mentioned on the show a couple times).
This is to say, an improvement may be made as opposed to what a person was previously eating (a bunch of sucrose and fructose?), and that may be enough, at least for some.