You need to see a doctor to get some answers, particularly to the issue of what type of diabetes you have and what treatment you should be receiving for it.
As to your question about an electric shock causing diabetes, I am afraid that I don't know the answer.
If it turns out you are type 2 and if your level of 300mg/dl is a fasting one, then it is unlikely that you had only been diabetic for a week, as it would take longer for your levels to get this high.