I have diabetes and I wear insulin pump, (which is a machine that is connected to the body via a pipe much like an IV, and it automatically delivers insulin to the body all day long and keeps the blood sugar stable) and a continuous glucose monitor, (which is a small sensor also connected to the body which continuously monitors the blood sugar levels). They both are attached to the body via an adhesive tape and are replaced every 3-7 days.
It is not hard to take them off but the thing is, once you take the tape off, you have to use a new one, and it is very expensive and difficult to afford.
So my question is, since the tape is not put on due to some wound, rather it is simply a facilitation and they are water proof, is it permissible to do ghusl while wearing it, knowing that the water won’t reach that part of the skin?
Moreover, what if someone intentionally does something that requires ghusl like masturbation or intercourse while wearing it? Should he wait every 3 or 7 days for the time to replace the tape to be able to do something like this for one day, and then wait another 7 days!?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

First of all, we ask Allah, The Exalted, to bless you with a speedy recovery, grant you good health and wellness, and guide you to what He loves and approves of. Verily, Allah is near, and He answers the supplications of those who call upon Him.

It is apparent from your question that you need to use the mentioned adhesive tape, and therefore it is treated as a cast. Fataawa of Shaykh Ibn ‘Uthaymeen read:

"If he attaches something to the parts of his body for a need, he should wipe over it when performing Ghusl (ritual bath) or ablution if it is attached to one of the parts of the body that must be washed when performing ablution, and wiping over it substitutes washing it. Based on this, we can say that if you become in a state of Janaabah (major ritual impurity) while this tape is attached to your chest or back, for example, you should wipe over it during the Ghusl. This would be sufficient, and you do not need to perform Tayammum, and your ritual purification is considered complete." [End of quote]

Accordingly, it is permissible for you to wipe over the aforementioned tape during the Ghusl for Janaabah or ablution if it is attached to one of the parts of the body that must be washed when performing ablution.

It is also permissible to have sexual intercourse while this adhesive tape is attached to your body. As for masturbation, it is prohibited in all cases, and it incurs grave evils. Shaykh Ibn ‘Uthaymeen said: “You should know that masturbation is prohibited, whether it is done by hand or by rubbing the genitals against the bed or by any other means because Allah, The Exalted, Says (what means): {And those who guard their private parts, Except from their wives or those their right hands possess, for indeed, they will not be blamed –  But whoever seeks beyond that, then those are the transgressors.} [Quran 23:5-7]” [Liqaa’ Al-Baab Al-Maftooh]

Allah Knows best.