I would guess at either timing sure to high carb content, or too much fat OR basal out a as usually if going high after the 2 hour mark. Would.have to do a basal test for that time period to be certain.
Could also be eating low GI carbs with your meal they release slowly into your body. Had that problem until I practically cut down the low GIs. I know it goes against current advice but it works for me
I do eat a lot of wholemeal foods but I inject after the meal and this usually works. I'm pitting last night down to the bit of cheese cake I had. Thought it would be ok after the gym but obviously not!