I haven't checked out the details of Hall's cough sweets. I will!
However there's a problem for many people in understanding the cconcept of carbohydrates.. Not all carbohydrates are digestible [sic, dietary fibre, which is cellulose] and not all the digestible ones raise blood glucose. Only the carbohydrates made up of glucose monomers do that. there are many other "base" units for carbs, such as, trioses, tetroses and pentoses[and probably heptoses and octoses too!]. None of these raise blood glucose, but all are in the strict sense carbohydrates.
thus the Americans, correctly, list cellulose as a carbohydrate in all their labelling. We separate it off.
It's all quite complex unless you have some knowledge of organic chemistry and metabolism.
the carbs which are important to diabetics are the glucose based ones, such as glucose bases sugars and starches. They are the chief culprits for raising blood glucose.
Hana