Diabetic nephropathy is kidney damage caused by diabetes. Persistently high blood sugar damages the kidney's filtering system, allowing protein that would normally be kept in the blood to pass into the urine.

In the early stages of diabetic nephropathy, small amounts of protein leak into the urine (microalbuminuria). As nephropathy progresses, the kidneys begin to leak large amounts of protein (macroalbuminuria). This means serious damage and can lead to kidney failure.

Diabetic nephropathy can often be prevented by keeping blood sugar levels within a target range. It is treated with medicine to slow or prevent further kidney damage. Getting regular exercise, eating a low-fat diet, controlling high blood pressure, and not smoking also may help people with diabetes to prevent kidney damage.