What is an average blood sugar reading for a man that weighs 325 pounds?

Same normal: You should have the same normal glucose levels as anyone else, however, it's going to be much harder for you to do that with your extreme obesity and Insulin resistance. Hopefully, you're on diet, exercise and weight loss, plus probably several medications for diabetes, cholesterol and blood pressure control.

Very variable: If the individual does not have diabetes, i would expect the sugar to be normal (i.e. 80). If the blood test were taken a minute after eating a dessert, it might be a bit higher. If he has diabetes, the sugar could be very, very variable depending upon how good is control is. If his diabetes is out of control, it could be very high--300s or even higher. If under fair control, it might be 200.