I have a cousin whose blood sugar levels often rise over 300s. This has been over a couple of years now. I am really concerned about him but unfortunately he doesn't seem to really care about himself and believes that the oral medications he's taking is enough. He shows no symptoms of diabetes at all.
My questions are:
1. How come very high glucose levels cause no symptoms at all? (no frequent urination, thirst, blurred vision, etc)
2. When one's blood sugar levels often rise over 300s, isn't it time to use insulin instead of just oral drugs?
3. Is there any factors other than food that may cause blood sugars to rise above 300s in several different occasions?
4. Is it true that non-diabetics' blood sugar will never rise above 120 despite of what they eat and how much? If this is not true, how high a non-diabetic blood sugar can rise?