Lot of people over 45 are diabetic, thought some could share their wisdom with a newbie, and at the same time enlighten the curious. He started making small changes in his eating habits immediately.
He eats very healthy now, with the occasional exception.
But as you undoubtedly know, your friend is still (at least technically) a Type 2 diabetic, even though his blood glucocse level is well controlled without oral medication.
The big difference for him is, he is able to manage his diabetes with diet and exercise alone.
The factor that is the biggest problem in dating is food, but it isn't that hard to cope with dietary restrictions -- because the major restriction isn't what you can eat but how much of certain things you can have.