After my transplant, my labs also detected high blood sugar. My husband just told me that it was called post transplant diabetes. It was really a worry for me because I had never been told that my blood sugar level was out of range. I had to test it daily with a finger prick and took insulin for a while. I had never had any indication of diabetes before that, and it as a new experience for me, just like it must be for your father. My doctors explained that it was caused by the high doses of prednisone that I was taking. As my prednisone levels were lowered, the insulin was no longer needed.
I remember that I had to check my levels for a while after I returned home. After the levels became stable, I didn't need to test or take insulin anymore.

It sounds like his doctors and my doctors are in agreement - it will improve as the meds are adjusted. 🤍

Hi, @luna69 I too had high blood sugar after my transplant. Before that I did have diabetes but it was mild and controlled with diet, no medications. After my transplant I did need to check frequently and take insulin. As with @rosemarya when they lowered my insulin the problem went away.
I do still have diabetes but my A1c is so low it's not even in the pre-diabetes range so I continue to not need any medications for it.
JK