Diabetic nephropathy is divided into five stages. In the first and second stages, patients generally do not have significant proteinuria. At this time, the pressure inside the glomeruli increases, and the glomerular filtration rate actually increases, which may result in an increase in kidney size. During this period, patients generally do not have obvious symptoms, and it is difficult to detect without detailed examination. By the third stage, patients develop proteinuria, which increases as the disease progresses, and patients may notice an increase in urine foam. When diabetic nephropathy reaches the stage with proteinuria, a prominent clinical symptom is edema. This edema initially appears in the bilateral facial and lower limb areas. As the disease progresses, some patients may also experience generalized edema, and can develop effusion in the pericardium, thoracic cavity, and abdominal cavity. Symptoms such as chest tightness, shortness of breath, difficulty breathing, pulmonary edema, and heart failure may occur.