Bless you, I think your son may have already worked out and noticed what some fruits have done to his levels before so avoids them. Taking extra insulin just to eat fruit is a no brainer, I used to love my fruit and based my breakfast around it with yogurt until I found out about dr Bernstein’s low carb lifestyle. Since then I’ve not eaten one piece of fruit. Get all my goodness from vegetables, nuts, seeds and salad stuff like lettuce, cucumber, green bell peppers, spring opinions and rocket. No vitamin or mineral deficiency either, in fact all the eggs I now eat haven’t effected my cholesterol and have my b12 levels right up there. Never felt better either.