I'm surprised at that spike. I eat the majority of my carbs in the evening, so around 25-30g?, and I barely need to take any insulin for it post gym session. How much are you eating? you could try Quinoa for a good grain replacement that has a high protein content, so it's good for you to bulk up if that's what you're after. I'd also recommend a split bolus if you're eating 40+ grams of carb in one sitting, especially for carbs with high fiber content like Brown rice and Sweet Potato, it's the only way for me to avoid the low/high swing.