Insulin is a glucose-lowering drug, and it is a normally existing blood sugar-lowering hormone in the human body, so long-term insulin injection has no serious adverse reactions, and it is not addictive and does not produce insulin dependence. The possible side effects of long-term insulin injection include the following: First, hyperinsulinemia, long-term insulin injection may bring about hyperinsulinemia, hyperinsulinemia is likely to lead to weight gain and aggravate the development of atherosclerosis. Second, hypoglycemia, long-term insulin injection, when the diet is irregular or the insulin dose is too large, it is easy to occur hypoglycemia, serious cases can cause hypoglycemic coma, or even death. Long-term insulin injection should pay attention to the rotation of the injection site to prevent repeated injection of the same site and produce fatty hard knots, or even fatty atrophy of the injection site, which affects the absorption of insulin. Fourth, insulin allergy, individual patients may have insulin allergy.