I find pre bolusing works wonders when it comes to highs! Just taking at least 20 g of insulin about 10-15 minutes before you eat can make the world of a difference. As for lows, you may want to talk to your doctor. If it's from panic injections when you're high, trust your first bolus and don't check again for at least a half hour. If it's coming down great! If not, make sure all your products are still good and only give a tiny bit more