This is why you should never purchase diabetic foods!!
If you go to the health shops you can buy sugar free sweets that contain no sugar, hence good for diabetics? WRONG!!
They contain typically 98% Carbs - Very bad for diabetics......!!
I agree that they aren't necessarily a good idea but not for the reason you say.
I've got in front of me a packet of Ricola sweets that are 'sans sucre' .The label says per 100g : carbs 97 of which sucres 0g, polyols 97g.
Polyols are nutritive sweeteners, that means that they have calories (about 2.4 calories a gram in my packet) . That's different to non nutritive sweeteners, eg. aspartame/saccharine etc, which have none. Polyols are carbohydrates but are not sugars or starches and
normally have very little effect on the glucose levels ( can vary a bit according to sweetner and individual reactions
In this case the ingredients tell me it's isomalt but it could have been others such as sorbitol, glycerol, maltitol, xylitol, and mannitol.
Research shows that isomalt doesn't do much to either insulin levels (in those that have their own) or glucose levels. If someone with type 1 ate a few of them and injected for them , they'd end up very hypo if they used the carb count at face value.
http://www.childrenwithdiabetes.com/d_08_b70.htm
However because they aren't absorbed they are fermented in the intestine. Again people react in varied ways but they can be very laxative and cause some people to get a lot of intestinal gas and feel very uncomfortable.