How do antihypertensive drugs work on the kidneys? What does it mean if an antihypertensive drug protects the kidneys?

People with renal insufficiency or diabetes often already have kidneys that are not functioning well, so medications like telmisartan or ACE inhibitors can be used to delay the degradation of the kidneys. For the person undergoing dialysis, the kidneys function very little, so the filtration of waste and the elimination of water is done with a machine. However, the machine is not as efficient as our kidneys, so the person must still take several medications to reduce pressure and eliminate water.