Thanks for writing to the forum!
I am sorry to hear about your husband. Diabetes does complicate matters. With a history of such a major surgery and diabetes I would advice you to get his kidney function tests done to check for his kidney function. This can cause fluid accumulation if kidneys are not functioning well.
Also a heart ECHO may be required to check for the condition of heart. Meanwhile restrict salt and fluid intake.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!
Some amount of weight gain is seen after bypass graft. This is because the heart has a lot of dead tissue, due to the presence of which, there is failure of the heart as a pump.It will take some more time to get resolved. In the meanwhile, let your husband be on a low salt diet along with the medicines.