A fruity odor of the breath occurs as the body attempts to get rid of excess acetone through breathing. This is a sign of Ketoacidosis, which may occur in diabetes. It is a potentially life-threatening condition. For type I diabetes your husband may not be injecting enough insulin before bedtime. I would suggest follow up testing by his PCP is in order to determine whether his insulin dose needs adjustment.
For an explanation of Ketoacidosis go to this link
Although my husbands breath smells fruity to me when he is asleep, he is not insulin controlled, but but type 2 medicaton controlled. His doctor says that his blood sugars are well controlled, and he even wakes with low blood sugar (2 m.mol), and has to get up and eat to correct this. He takes his own blood sugars every day as well as 6 monthly testing by the diabetic nurse, but I am worried about possible Ketoacidosis.
Take your husband to his doctor ASAP. Taking type 2 medication then waking with a 2 mmol/l reading is dangerous. Getting up to eat something to bring normalcy says he is a type 1 diabetic, not enough glucose. The fruity breath points strongly to Ketoacidosis.