check it out this info. relevant to it might be helpful:
" The addition of fat (soybean oil) to a grain meal will affect glucose and insulin response to feeding, according to this feeding trial.
Nine Thoroughbred horses were used in this two-period switchback design experiment. Five of the horses were in training and were physically fit, and four were untrained. During period one, each horse was fed 2.27 kg (5 lb) of a grain mix, which consisted of 72% oats, 20% corn, and 8% molasses at 7:00 a.m. Five of the horses were also fed 200 ml (170 g) of soybean oil mixed into the grain. At 8:00 a.m. each horse was given 2.72 kg (6 lb) of mature bluegrass hay. Blood samples were taken from each horse by jugular catheter before feeding and at 1, 2, 3, 4, 6, 8, 10, and 12 hours post feeding. Water was available to the horses at all times. The same procedure was followed two weeks later with the soybean oil added to the grain of the four horses that served as controls during the first period.
Blood samples were collected and analyzed for lactate, glucose, and insulin at the conclusion of the study. Blood glucose was significantly lower one hour after feeding when soybean oil was added to the diet. Glucose remained lower for 3 hours post feeding. After 6 and 10 hours, blood glucose was higher in the fat-supplemented group. Insulin was lower in the fat-supplemented group 1 hour after feeding. After 8 and 10 hours, insulin was higher in the fat-supplemented group. Plasma L-lactate tended to be higher in the control group 4 hours after feeding and higher in the fat-supplemented group 6 hours after feeding.
These data suggest that the addition of fat (soybean oil) to a grain meal will affect glucose and insulin response to feeding. These effects are independent of the amount of carbohydrate in the diet and may be due to differences in the rate of gastric emptying when fat is included in the diet.
Basicallly the addition of oil in a high carb ration serves as a "ceiling" for the glucose insulin response.....what I am trying to say is the peak is lessened. The body still responds and as a result slighly elevated insulin/glucose levels lag several hours behind. What is obvious tho is the extreme peak is de-amplified with the addition of oil.
They certainly speculate that gastric rate/flux may be at play here. But this appears to be "feed them and weigh them" type experimentation. By that I mean feed them something and measure the response. They really do not address the mechanism nor expand much past gastric flux.