IF any scientific research has been done on this subject it will have been done by the original licence holder & should have made its way into the leaflet which comes with the tablets. Who reads these? I would be wary of what my GP or pharmacist advises as I suspect they don't read them either.
Most types of tablets are best taken with food rather than on an empty stomach in my experience.
I am taking Sukkarto (the slow-release Metformin) as I had issues taking the normal ones. The advice (not easy to find!) in the leaflet says to take them with evening meal.