What should the average blood glucose levels range?

my husband is diabetic, but refuses treatment, doctor visits, or even regulation of diet. He weighs about 150, is 5' 7" and is very active- 22 years old. His levels every time we used the blood glucose tester are 200- 250. Is this normal? What should they be? I am hypoglycemic, 102 and 5' 7" 23 years old and my levels are 90 -120 when im feeling normal. Does anyone have any advice on how to convince my husband the severity of not treating his diabetes and how important it is to eat right? As well what level should his blood glucose range on average?