All evidence shows that creatine has to be accompanied by insulin to be effective. This is quite plausible considering creatine is a much larger molecule than glucose, which requires insulin to permeate the membrane of muscle. Acknowledging the fact that creatine is roughly 50% glucogenic (can maximally revery to 0.5g of glucose per g ingested), you do receive an insulin response from proteins. The only problem with taking creatine with protein alone is that protein (aside from hydrosylates) elicits a much less rapid pancreatic response than do carbs. Assuming you the creatine remains in circulation long enough for you to receive an insulin response, there is no true reason for a protein/creatine combo not to be perfectly effective. In fact, I think that by ingesting creatine with carbs, you may better utilize it considering protein's retardant nature of gastric emptying. Since protein digestion is quite complex, it stays in the gut for a while, and it holds other nutrients in there with it. By holding creatine in the villi for a longer time span, you may get (for lack of better terminology) a "time-release" effect from the creatine. This means less insulin is required from optimal assimilation. This is really good news if you are trying to monitor carb intake. Then again, most of this is my theory...
Coe