Xerostomia or Dry mouth is a fairly common problem, I got it a year ago. As part of finding a solution a new Diabetic nurse recomended I asked for a free trial of a Libre 2 plus constant glucose monitor to see the exact impact of every meal and every medication and change of medication timing. It was a revelation, I saw that my biome was unbalanced and could process things like porridge and shredded wheat any flour product immediately, no long delay like we are told whilst stews, roasts, English breakfasts did not move sugars at all. So my "good diabetic control" wasn't good at all but with changes within 2 weeks my projected HBA1c was 6.5% or 48mmols.
I could also see the sugar lower and increase as the drugs with shorter effective perids run out of steam so could fine tune the taking of Dapagliflozin and Glicazide to match my peak sugar (meal) times.
I highly reccomend trying this device.
For me, most of the problem seems to be eating wrong diabetic recommended foods and taking tablets at wrong time of day and the need to stop taking Dapagliflozin altogether.