Consistent Glucose Monitor And Ghusl
Brother your situation is no different than other medical situations, such as having patch or dressing on a wound or a cast on a broken bone, etc. The need to constantly monitor sugar level is enough of a reason to allow it.
Dr. Irfan Shahzad Sahab ( @Irfan76 ), kindly give your juristic opinion on this issue.
It depends upon the medical opnion. If the doctors allows you, considering the best of your interest, to remove it during Ghusla, you can take it off, but if he suggests to not to take it off, you can take bath while putting it on. In such matters, the principle is to provide EASE, as Quran says: يُرِيدُ اللَّهُ بِكُمُ الْيُسْرَ وَلَا يُرِيدُ بِكُمُ الْعُسْرَ God desires ease for you and does not want to be harsh with you. (2: 185)