Insulin is advocated to help lower blood sugar in diabetic patients whose blood sugar is more difficult to control, and insulin is one of the safe and effective medications. Diabetic nephropathy, especially the stage of massive diabetic nephropathy, creatinine may rise, when oral hypoglycemic drugs may bring the risk of lethal hypoglycemia, mainly because the degradation and excretion of oral drugs in the body is affected by the kidney function, which will continue to lower blood sugar leading to severe hypoglycemia or lethal hypoglycemia, which is very dangerous. Because hypoglycemia can easily lead to coma, when realizing hypoglycemia, you may not even have the strength to call or call someone or even die in your sleep, so hypoglycemia is terrible. When CKD stage 3 which means blood creatinine >133μmol/L, most of the oral hypoglycemic drugs can no longer be used, and the few drugs that can be used should be considered to be reduced or discontinued or used with caution. Insulin is the only glucose-lowering drug that can be used throughout the whole process. In the stage of renal insufficiency, appropriate adjustments need to be made according to the level of blood sugar and the level of renal function, and the dose is usually reduced, also for the purpose of preventing hypoglycemia.