I don’t know anything about IPMNs so sorry I can’t help you out with that topic, but there are several in this forum who have experience or knowledge about it.
Regarding diabetes potential: I believe it depends on how much of your pancreas is removed during the surgery. Islets of Langerhans “which produces most of the insulin are located primarily in the body and tail of pancreas. I had 70-75% of my pancreas removed during my distal surgery and I sure have a significant blood sugar problem which is probably also very prevalent because I love frozen yogurt and doughnuts, unfortunately! If you had even borderline diabetes or controlled type 2, then you may have it after. I wear a blood sugar sensor on my arm (freestyle 3), and it does help tremendously to keep track of blood sugar levels, and I take insulin before every meal. I hope you receive the guidance you need about the IPMN. Always consult with another dr for their opinion if you have doubts about your current care.