I was on Metformin too until recently and hated the resulting side effects - particularly on trips to the toilet. My GP suggested I could try the Oviva TDR program, which i was happy to switch to as it meant leaving medication behind at least for now. 10 weeks in and i've lost just over 10 Kg (target is 15Kg), on a combination of 4 shakes/soups per day (amounts to around 800 calories a day) One downside of this program is the soups are totally disgusting and despite having had a sample pack i still ordered a tub of each of the chicken and vegetable. These things have absolutely zero flavour and are more like eating sawdust, and can only be tolerated by overloading on chilli flakes and paprika in the mix to fool( or more accurately numb) the palate into thinking they are ok. The shakes are passable though and the chocolate one in particular makes a decent hot chocolate (or add a spoonful of coffee to make a mocha) to start off the cold mornings with. The other thing I have found difficult to cope with is the no-alcohol requirement, which as a real-ale lover has been a definite chore to maintain.
I'm pleased with my progress so far but, of course the real work, starts when i start introducing real food back into the mix, and trying to keep that weight off. Especially as living on my own I've always gravitated to the easy option of cheap ready meals or takeaways. I have, though, started collecting recipes that I can use to maintain a healthier (and low-carb) diet. It helps that star chef's such as Tom Kerridge, anf The Hairy Bikers are known to have gone through the process (not necessarily TDR programs) and have a wealth of recipes to glean support from.
My main goal is now not to rely on medication to control / smack this into submission but to use diet/exercise to achieve the results I've managed to date.
Good luck with your journey