Nephropathy means kidney disease or damage. Diabetic nephropathy is damage to your kidneys caused by diabetes.
The kidneys have many tiny blood vessels that filter waste from your blood. High blood sugar from diabetes can destroy these blood vessels. Over time, the kidney isn't able to do its job as well. Later it may stop working completely. This is called kidney failure.
Diabetic nephropathy is treated with medicine to slow or prevent further kidney damage. It can often be prevented by keeping blood sugar levels within a target range.