I tend to lightly oil the tray or dish, just to ensure the veg doesn't stick, the lightly drizzle when they're on there. I have a few home made infused oils I sometimes like to use, to add a little extra something; garlic and/or chilly, for example.
Great advice above. All i can add is to suggest that if your body has not yet adjusted to the current dose of metformin a day, then it would be bowel-shaking madness to increase the dose so quickly!
I urge you to stay with what you are doing, then increase slowly after your body learns to cope with this dose. If you need to discuss it with the surgery, but don't just follow their instructions if it is causing you distress. Any experienced metformin prescriber knows that people adjust to it at different speeds.
Acceptance of health treatment claims that are not adequately supported by evidence. I dislike it when people sell ineffective and even harmful alternative health products to exploit the desperation of people with chronic illness.
If you can drink loads (water!!) and try just a bit more salt as mentioned above, hopefully you'll feel fine soon. Someone advised on here to use good salt, so I switched to finely ground sea salt rather than my up until then table salt - something to do with more minerals/less impurities.
My understanding is that between sea salt and table salt the minerals should be the same, and the only "impurity" I can think of would be iodine, but that is good for us because it prevents iodine deficiency, which involves goiter.