So sorry to hear that your husband is at risk- has he been to a doctor to get evaluated?
This article has some good general information for understanding diabetes and what a good glucose reading is:
http://www.medhelp.org/diabetes/articles/The-ABCs-of-Diabetes/2327
It's important that he get some goals for his levels from a doctor though, the doctor will be able to evaluate his specific case and will know better what levels he should be maintaining for fasting, and before and after meals.