Lucozade was traditionally a very high-glucose therapeutic drink that was frequently bought by people visiting hospital patients.
More recently, between product diversification and the sugar tax, there are so many variations of the drink today that the glucose content is a guaranteed source of confusion. But regardless of which lucozade product is in question, it's definitely no longer a high sugar drink and there's no good reason for diabetics to use it. "Lift" is a good product for treating hypos with 15g glucose; and there are several low sugar drinks available such as water or any of the "diet" drinks when sugar is not needed. I would suggest to get your mother drinks where the sugar content is clear to all, rather than depending on (possibly jaded) junior doctors to be up-to-date on the ever-evolving soft drinks industry.