That’s awesome, I have never had a twin 
. Congratulations on your weight loss and being and getting your blood sugars under control, again that is simply fantastic.
So here the rub, I am not sure that I totally agree with your hypothesis and here is why. While metformin does “slow down” gluconeogenesis, it does not totally suppress it. Your liver will still continue to make small amounts of glucose that your body needs to function even if you are not eating any carbohydrates. In fact, metformin should help increase your insulin sensitivity, which lowers your blood sugar.
In addition, metformin should not have any effect on decreasing ketone generation/production, rather it should help promote ketone generation/production. When there is an absence of glucose, your liver should breakdown stored fat into ketones which your body can then use for fuel when you are fat adapted.
Now, I have not seen any specific studies that show that metformin actually helps or hinders keytone production, and my logic may fail me. But if I understand the process of fat adaptation and keytone production, then having less glucose to burn for energy, should cause your body produces more keytones. I am sure that if I am incorrect, there is someone on here that can explain it better than me.
Again, you are to be commended on your progress, I am glad that the ketogenic way of eating has reversed your diabetes and most likely saved another life.
So, didn’t do before and after pics, but came across 2 fb pics from before and after my 45lb weight loss. I lost 45 lbs in 120 days (September through December) by cutting all grains, sugar, and processed foods and doing intermittent fasting. I did go all the way to keto in October and I’m still keto now. I’ve been coasting so far this year and maintaining that 45 lb loss without any additional effort and only fasting 16 hrs/ day 5 days per week - only occasionally tossing is a 2 or 3 day fast.