The DVLA say this -
Diabetes - Managed by tablets which carry a risk of inducing hypoglycaemia (this includes sulphonylureas and glinides)
So it seems the list is not limited to only sulphonylureas and glinides. They must class your Linagliptin as one of the at risk drugs I guess which does seem odd as it is a DPP4 inhibitor and meant to not cause hypos particularly. It is a good idea to test as an HGV driver anyway, be sure to be aware of the rules which are on the DVLA's website reference levels, ie 5 to drive, below 5 and above 4 correct before driving, below 4 correct and wait 45 mins.
Ali