Given you are on insulin you will need to be careful so you don't end up having a hypo. You really need to speak to your medical team and get some advice from them.
I am on no medication so I am definitely not an expert. I suggest that the first thing you may want to do is to actually start a food diary- recording what you eat (the amount of carbs is important) the level before you started eating and the levels at 1, 2 and 3 hours afterwards. This would at least give you some idea about the effect the food is having on your levels- it may also assist your medical team in recommending actions for you to take to bring your levels down in a safe way.
When you say high, what levels are they? Have you been given ketone testing strips? Were you given guidelines by whoever prescribed the insulin, on what to do if your blood sugar as high?
Sorry for all the questions, but it helps those replying to your question to give the best answers.