Yours is not a sulphonylurea nor a glinides is it? Therefore it’s the second part of that quote and there are no limits given, in fact that part doesn’t even mention hypoglycaemia.
again - The wording of how your reported the drs comments initially it made it look like she was wrong. Then you changed what she said and it no longer appeared wrong. However her advice appears to be related to insulin, sulphonylureas and glinides only by the looks of the above gov page. Nowhere - for anyone - does it say you have to be in the 5’s unless coming out of a hypo (under 4). If you’ve gone under 4 you have to deal with it and then wait 45mins after reaching 5. You can drive in the 4’s on these if you have eaten something and not been hypo. For other meds there are no numerical requirements.
DVLA don’t need to give medical advice just clarify what they print. Ie what rules apply to GLP-1 receptor agonists of which Trulicity is one. In your shoes I’d phone then back and get someone to talk sense, in order to reassure you.
This is your job and obviously a huge cause of worry for you. Keep going with DVLA til you get a clear answer or are happy with what you’ve read on official pages.