The early symptoms of diabetic nephropathy primarily include the presence of microalbuminuria, which is characterized by an albumin excretion rate of 30 to 300 mg per 24 hours, or a ratio of albumin to creatinine in spot urine ranging from 30 to 300 mg/g. However, this value needs to be tested three times over six months, with at least two of these tests meeting the above criteria for a diagnosis. Additionally, in the early stages of diabetes, patients' blood pressure tends to be within the normal range, but there is a trend toward elevation. Some patients may experience changes in the diurnal rhythm of their blood pressure, and the glomerular filtration rate may slightly increase or remain within the normal range.