Bridget,
Low sugar can cause a person to feel very negative, gloomy, fearful, opressed. So those kinds of thoughts may be a part of it.
But most people have trouble with those kind of thoughts at certain times and it can have nothing to do with diabetes. It can be an emotional matter or even a spiritual matter. Sometimes I have to pray, listen to good, upbeat music or read something spiritually uplifting to help myself when I hear persistent, nagging negative thoughts. If you believe in prayer, I would suggest you pray and have someone you trust to do so with you and see if you can't lift this obsessive negativity! You shouldn't have to live like this every day!