This month, from the American Journal of Clinical Nutrition:
Distinctive Postprandial Modulation Of Βeta Cell Function And Insulin Sensitivity By Dietary Fats: Monounsaturated Compared With Saturated Fatty Acids, AJCN, September, 2008
"High-fat meals increased the postprandial concentrations of insulin, triglycerides, and FFAs, and they enhanced postprandial β cell function while decreasing insulin sensitivity."These were postprandial measurements (taken shortly after eating), as opposed to fasting measurements. It makes me wonder how useful an oral glucose tolerance test (OGTT) is, since it only administers glucose, not fat - and most people consume some amount of fat in their meals. If fat can increase insulin resistance, you may not be able to clear glucose after an average meal as effectively as you did during an OGTT.
"These effects were significantly ameliorated, in a direct linear relation, when MUFAs were substituted for SFAs."
"The data presented here suggest that β cell function and insulin sensitivity progressively improve in the postprandial state as the proportion of MUFAs with respect to SFAs in dietary fats increases."
MUFA - monounsaturated fatty acid (olive oil is a good source)
SFA - saturated fatty acid (meats and dairy fats are good sources)
FFA - free fatty acid
Dietary Fat Raises Insulin Levels, May 2008
Type Of Fat Eaten Affects Insulin Levels, May 2008
The More Fat You Eat, And The More Saturated That Fat, The Higher Your Risk For Diabetes, September 2008
Photo of Whole Foods Cheddar from Kirk Samuels' 365 Cheeses site.