A couple things leaped out at me reading this. What about insulin resistance? Do people with high insulin resistance have less of an effect from sugary snacks? On the flip side, how about exercise? Do people with a lot of sugar stored in muscles and a more optimum processing of sugar do better on these things? To put this more generally, the author seemed to be reporting from a deterministic viewpoint, i.e., whatever…
Nope. The dopamine response from eating sugar is completely independent of the insulin response. Unfortunately people with type 1 diabetes still get a dopamine response from eating candy and don't get one from injecting insulin -- life would be so much better if those were reversed!