INS and diabetes mellitus: In diabetes, blood glucose significantly increased, but the function of islets was impaired, and insulin secretion was decreased (as shown in Figure 3G, the 33.3mmol/L glucose + 0ng/ml insulin and 33.3mmol/L glucose + 5ng/ml insulin groups), at this time, the effect of insulin on the expression of miR-21 was weakened, but high concentration of glucose up-regulated the expression of miR-21 significantly.