Hi @margaretbannan1948 and welcome to Mayo Connect. I have not had a Whipple for my pancreatic cancer, but I do take insulin daily to help with my compromised pancreas due to cancer. Prior to my pancreatic cancer diagnosis, I was on metformin for a few years. I did a search of previous conversations around your question. To my surprise, this link is the only conversation that came up. There isn't much there. I actually expected to find something more helpful.
https://connect.mayoclinic.org/discussion/high-a1c/
I am hopeful that others with more direct experience with metformin post Whipple will respond. Do you have a specific question or two to ask, so we can help the responders address your concerns? Thanks.