Is my obligatory bath valid if I wear a continuous glucose monitoring (CGM) device on my arm that stops water from flowing over that area?

Summary

Wearing a CGM device during the obligatory bath is treated like wearing a bandage (jabirah). The patient bathes as usual, running water over the whole body including the device area, and then performs tayammum for the part that water does not reach. If dust for tayammum is hard to obtain, he may follow the second Shafi'i opinion (qaul qadim), which does not require tayammum after purification. If the device was put on while not in a state of purity, obligatory prayers in that period must be made up according to the final Shafi'i position, though if the period is too long he may follow the Maliki, Hanafi or some Hanbali view that does not require making them up.

Written in our own words from the original fatwa — check the source before acting on it.