Once we are in Nutritional Ketosis (we are burning mono, poly and saturated fats for fuel, i.e. we are driving the Kreb's Cycle with beta oxidation not glycolysis to produce ATP) we are eliminating the constant need for insulin to push glucose in tissue. So yes many athletes who are carb loading are in some degree of insulin resistance. When burning fat we switch to being insulin sensitive, far superior and natural to our bodies. Now when we ingest carbs we can very efficiently convert that into glucose for quick energy. Hence we are using carbs on top of a large fat reserve base to be metabolically flexible in how we generate energy.
Another key point is to watch your intake of protein. Remember once you hit the protein level your body needs the excess will be converted to glucose through gluconeogenesis, not what you want to do. Many times I see athletes using these high protein shakes all the time while training and don't realize why they are having the crashing results. It will be hard to be in Nutritional Ketosis with extra protein loading. Protein intake should be calculated roughly 1.0 - 1.5 grams per kg of ideal body weight. The key here is ideal weight. The rest is mainly fat and once in ketosis approximately 30-50 grams of carbs per day, each person is a little different, but testing initially with a meter and blood test strips will help you determine where you need to be.
Knowing how to strategically use carbs for high performance energy
Once in Ketosis the real art and science is to learn how to use very specific carbs to load at specific times in training or competition to get the optimal use of both fuels. Whether you are a triathlete, figure skater, tennis player or wrestler you can tap both fuels for constant deep energy stores AND fast bursts of energy when needed. Your able to use both fuel tanks.