Hiya - I am Type 2.
If you are doing 1200 step you can stay on the Metformin but if you come down to 1000 or below you cannot continue to take them - the CD booklet tells you this.
You will have very low sugar readings, if you continue to have them you can cause more damage than you are trying to correct by dieting.
I started on the 1200 back in Jan did that for a month then did 790 for 5 weeks and now I am SSing I have been off my Meds since end of Jan beginning of Feb and I have just had a blood test at the docs and I got a hug and a kiss off the Diabetic Nurse, I am on NO meds at all now and I was on 6 Metformin a day back in October 06 + Atorvastatin + Omeperazole (Heartburn).
When I had my last test in Dec my long term was 7.7 and fasting 6.4 it was 6.2 long term and 4.7 fasting on 12th March.
Just be careful and monitor yourself if you have some 'FUNNIES' low sugar rushes then cut the metformin down or at least discuss it with your Nurse/GP.
Hope this helps - you will have others come back to you about this as you are not the only one.
Hugs and good luck - Best thing I ever did.
xx