[will_brown]

Type 2 is insulin resistance. In other words your body produces insulin to clear sugar from the blood but the body no longer responds (actually clears the sugar from the blood) to insulin.

The resistance (type 2) is built up over time (historically it was “adult onset”) to insulin spikes. I don’t believe saturated fats introduce sugar into the blood, so they don’t cause insulin spikes, which means they don’t contribute to resistance (at least not directly).

In a roundabout way they may contribute to a surplus of calories and the storage of fat, ultimately causing obesity, which does seem to speed up the resistance to insulin. But all things being equal the same surplus of calories on a high carb diet will be more detrimental because there will be insulin spikes and the insulin will also enlarge fat cells allowing the body to store more fat (ie become obese more efficiently).

[ZeroFries]

https://www.ncbi.nlm.nih.gov/m/pubmed/26615402/

[will_brown]

Yes the study suggest high fat diets may effect insulin sensitivity....so long as the test subjects are consuming carbs ALSO and triggering insulin. In other words the didn’t test effects of high fat diets while subjects were otherwise avoiding insulin spikes.

So yes eating fats is an issue while eating carbs and spiking insulin. You won’t find a single medical case of T2D where the subject hasn’t repeatedly spiked insulin with carbs/sugar.