There is no "secret" here. While saturated fat might play some role in type-2 diabetes (there appears to be a genetic factor for some patients), the immediate cause of insulin resistance is excessive carbohydrate intake. The Virta Health approach of nutritional ketosis appears to be quite effective and sustainable for many patients.

https://doi.org/10.1007/s13300-018-0373-9

https://doi.org/10.1016/j.nut.2014.06.011