Firstly don't be so hard on yourself, running high means glucose isn't getting into your cells so you will be feeling knackered, hence the need to eat rubbish food, it's a vicious cycle but also systemic due to the high levels of glucose in your blood.
Do you know why you're running high ? So is it illness, infection, hormonal, bad insulin, bad injection sites ? There's many reasons for running high but finding out is important as it will help in regards to treatment.
Have you worked out what your correction dose is to bring your levels back into range ? I hit insulin resistance when my levels start climbing, so I have to correct 20-40% more with quick acting insulin the higher my levels go. If I go really high then I change insulin and depending on the time of day I really attack it with insulin and testing more frequently, so every hour minimum during the daytime, I don't do this at night as I will need to sleep and its impossible to test then, I also drink loads of water to help flush the excess glucose out of my kidneys, keeping hydrated is really important.