Insulin adverse reactions include the following: 1. Hypoglycemic reactions: when the insulin dose is too large, it can cause hypoglycemia in patients, and the drug dose needs to be adjusted in time; 2. Allergic reactions: because insulin is a biological agent, it contains certain chances of allergic reactions. The common manifestations are wind mass, rash and itching, and in severe cases, chest tightness, shortness of breath and respiratory asphyxia can be produced. It is necessary to change the insulin injection variety in time; 3. Metabolic disorders: For obese patients with type 2 diabetes, long-term insulin injection can lead to weight gain and aggravate metabolic disorders. For such patients, long-term insulin use is not recommended.