Hi and welcome from me too.
We all understand how overwhelming and confusing it is in the beginning, so do not feel that you are alone in this. Things will slowly start to make sense and this forum can certainly help you with this journey and many people have had some quite miraculous results from changing their way of eating. Some have managed to come down from very high readings and push their diabetes into remission and even come off medication and maintain their remission through diet alone, but it takes a bit of getting used to and a will to change.
It would help to know some information about your husband's diagnosis.... Has he been diagnosed as Type 1 or Type 2 diabetic?
What, if any medication has he been given for it?
Do you know his HbA1c reading as that tells us roughly where on the diabetic scale he is.... I am guessing it may be very high since he was hospitalised.
Has he been given a Blood Glucose Monitor, to take readings from a finger prick blood spot?
As
@HenryBennett says, it is about all carbohydrates not just sugar as many people at first assume. Carbohydrates are both starches and sugars and the body breaks them all down into glucose which is absorbed into the blood stream and gets a bit stuck there in us diabetics. Reducing the amount of carbs we eat will mean that less glucose goes in and gives our body a better chance of coping with it.
The easiest way to do this is firstly to cut back on the obvious sweet stuff like cakes, biscuits, sweets/chocolate and added sugar but it may also surprise you to know that fruit in all it's forms (fresh, dried, canned and juiced) is also high in sugar and needs rationing. Then there are the starchy foods like bread, pasta, rice, couscous, potatoes and particularly breakfast cereals which are usually a combination of sugars and starches. Reducing portion size of these items is equally important to manage your husband's diabetes.
It may seem like there is not much left to eat, when in fact a low carb diet can be quite enjoyable but it does take a bit of getting your head around. Perhaps if you tell us the sort of things he currently eats for breakfast, lunch and evening meal, we can perhaps make alternative low carb suggestions. We do need to know about his medication though as that needs to be reflected in the advice we give.
Look forward to hearing back from you when you have time.