According to the papers in Jaminet's latest safe starch post, the cultures that eat the most carbs seem to have the best insulin sensitivity. I believe Carbsane has also reviewed quite few papers showing that glucose increases insulin sensitivity.

EDIT - For me personally, exercise and intermittant fasting has seemed to help a fair amount too.

If fasting insulin levels are an indication of insulin sensitivity then so far I've not been successful at using anti-inflammatory therapies to improve it. I have a couple of thoughts about this: one is that Stephan makes a compelling case that "excess fat mass, particularly enlarged fat cells, is the ultimate cause of insulin resistance." So if you buy that, then if you have excess fat, losing it is a priority.

Second, I've read that ~14% of the fat burned from storage is PUFA. So by my fuzzy math, a person losing 2 pounds in a week metabolizes the equivalent of 10-15g of omega 6 fatty acids per day even if dietary omega 6 is really low. I haven't found anyone who has looked at the real impact of this, but I'm guessing that if stored body fat is from a crappy Western diet, it cannot be good! But it is what it is, it's not exactly like keeping the fat on would work for me.

Finally, my own personal feelings is that aside from a basic anti-inflammatory diet, exercise is really the best option for increasing insulin sensitivity. With my whacked back, this has been hard for me (tho I just tried doing a mini-tabata in the pool on Wednesday ... that may work!).

Omega 3 is anti-inflammatory and improves insulin sensitivity.

Magnesium, chromium improve sensitivity aswel, and exercise is king.