Hi
@ashleyp, there are a couple of topics that discuss this in great detail. These are here:
http://www.diabetes.co.uk/forum/threads/insulin-load-index-most-ketogenic-foods.75704/ and here:
http://www.diabetes.co.uk/forum/threads/how-does-protein-affect-blood-glucose.75156/
There are essentially two processes going on. The first, that you have already identified, occurs immediately after eating, when your body believes it needs to release insulin to aid the absorption of Amino acids and glucagon to counter the blood sugar reducing effects of insulin. As you have no insulin, you just see the bg level rise.
There is also the second effect of high protein, which is Gluconeogenesis. This is the process that the body uses to allow the liver to convert protein to glucose. In a non-diabetic, insulin regulates this process, but with subcutaneous injections, more of the insulin goes to peripheral organs so it is less controlled. This results in a slower conversion of excess protein (not being used for muscle repair) to glucose.
Basal rates (whether pump or MDI) are typically designed to cover the function of the liver in a steady, fasted state. In the link to the second topic above, I discuss some of the approaches that you can take to dealing with this effect when on MDI.
Various foods generate different responses. I think the key to this is the fat content of the foods, in line with Marty's paper in my first link. In my experience, Whey protein shakes lead to an almost instant bg increase, eggs are nearly as big a spike followed by chicken breasts and pork and beef (dependent on leanness) in terms of the rate of bg increase. This also affects the timing of insulin you might take with these foods.
Typically when you discuss this with medical professionals, especially DSNs, very few of them understand it. In Dr Bernstein's Diabetes solution, he recommends injecting your Insulin:Carb ratio for half the weight of protein and Marty's discussion recommends 0.54 x the weight of protein.
Ultimately what I find is that for a high protein meal (e.g. 80g protein in a single meal) I need to inject 4u of insulin ahead of the meal and then 1.5-2u at 1.5 hourly intervals to maintain control for the next three hours. On a pump this is obviously easier.