@cupOtea - There are many types of catheters and there is no telling what type she had.
However, it sounds like if she was a diabetic and at home getting treatments with dialysis involved, she had some type of catheter system that was being used to deliver probably something called CAPD, or continuous ambulatory peritoneal dialysis.
If she was able to walk around pulling a stand with a hanging bag attached to it, that is what it probably was. Gravity was making the contents of the bag go into her abdominal cavity and was cleaning fluids that went into her body and then they were being removed into the bag along with wastes from the body. That is what this process does in replacing the normal job the kidneys do, which is filtering our wastes and getting rid of them. Usually the process is repeated about 3-4 times daily.
Great care needs to be taken when doing this process in handling the catheter tips, etc as infections can set in. Family members are usually taught how to do this and help with the procedure.