Is it true that taking Insulin AFTER you eat works better?

My girlfriend is 13, and she worries me A LOT because he sugar tends to be high gluclose (over 600) at least once a week, and she takes care of her Type 1 Diabetics(was not born,she got it at 10) very well...she has the Insulin Pump, and she takes the Insulin BEFORE she eats... and sometimes like every few days she'll have 400 or 500 ...sometimes 350 or something, blood sugar..which is high. and she doesn't know what else to do..because she changes her site properly, she does everything...
Should she start taking Insulin AFTER she eats? I heard (and she heard) that taking the Insulin AFTER she eats will help balance out the blood sugar and might work more and will prevent her to have high blood sugar..... she shouldn't be having over 600 once or twice a week...it's very dangerous..she could get a stroke/seizure anything terrible from that..and it worries me so much, and she gets scared as well. thank you.