We have several diabetic people as clients. The philosophy for over 80s is "whatever you want". Meds can be changed accordingly, if necessary. We have one who carefully uses canderel for drinks and cereal and eats sweets through the day. The nurse tells him to carry on, we check it regularly and she works out his medication from there.
It all comes down to blood glucose levels and honey ends up as glucose in the blood. To me honey doesn't taste as sweet a sucrose so I would probably end up eating more glucose if I used honey as a sweetner. But I'm not a diabetic.
Honey is no more natural than sucrose and in many cases 'natural' products are no healthier than the alternative and in some cases a darn sight worse.
Pixie, glucose is a carbohydrate as is starch or cellulose which would take forever to digest. It's a matter of getting a best mix of quick and slow release carbohydrates.
I'm with Woofgang all the way on this, its his life let him have sugar if that is what he wants! As long as he is aware of the risks he can make his own choice.