practicing medicine without a license.!! - problem is you see a Dr how many times in a year ? for me 4 times a year. your just a name on the records,,, also depends on the age of the Dr, an older Dr is happy to continue your Prescription, a younger Dr will try to put you on the newer or lastest Meds + sometime I have no idea until I get home meds have changed... i live with my medical problems 24/7 so I am the best person to know what is working..
on the other hand go to a Pharmacy and see the Pharmacists [Pharmacists have also done 4 years traming but more on effects of different meds]
some years ago my Prescription changed from the Hospital, had problem 90 days later spoke with the Hospital Dr, your get used to the Meds was the answer there good ??
Spoke with the Pharmacists said that Med is the problem, he was right
As for Metformin, have taken for 34 years, I have kidney problems CKD , again what Dr you see some say Metformin is good for CKD others say is bad ?
As for self medication, told many years ago by a Hospital Dr, take BP meds + Diabetic meds according to you readings every day... no way would I take my Insulin if my reading was below 70,,, like way found for me taking a smaller dose of BP meds twice a day works better then the subscribed 1 tablet mornings