Diabetic nephropathy needs to be combined with a history of diabetes, renal function related tests, combined with other complications of diabetes to make a comprehensive judgment. 1. History of diabetes mellitus: diabetic nephropathy should be suspected when type 1 diabetes mellitus with a duration of more than 5 years and type 2 diabetes mellitus diagnosed with persistent microalbuminuria. 2. Renal function related examination: clear history of diabetes mellitus, and has gradually appeared micro-proteinuria, or even a large amount of proteinuria, such as accompanied by nephrotic syndrome manifestations (hypoproteinemia, large amount of proteinuria, edema, hyperlipidemia), both consider the diagnosis of diabetic nephropathy. 3. Other complications of diabetes: diabetic nephropathy should be considered when combined with other complications of diabetes, especially fundopathy. Diabetic nephropathy has an insidious onset in the early stage, often with no obvious clinical manifestations and a poor prognosis. When diabetic patients have the above symptoms, they should consult a doctor as soon as possible, and improve the prognosis as much as possible through early treatment.