When pregnant women use insulin, too large a dose may cause hypoglycemic reactions, and a small number of pregnant women may have allergic reactions. It is recommended to apply insulin rationally under the guidance of a doctor. Insulin works by binding to cell membrane receptors in the liver, adipose tissue and muscle. Its main function is to increase transmembrane transport, facilitate glucose uptake, promote intracellular glucose oxidation and glycogen synthesis, thus lowering blood glucose. 1. Excessive or inappropriate dosage of insulin in pregnant women may lead to hypoglycemic reactions in patients. 2. Insulin-induced allergy is rare. In case of allergy, the patient may have skin rash, itching, and in severe cases, it may cause chest tightness and shortness of breath, which requires immediate medical attention. Pregnant women should start reasonable dietary control and exercise therapy after finding high blood sugar. And immediately seek medical advice and start insulin treatment as soon as possible under the guidance of the doctor. Any problems during the use of insulin should consult the doctor and take appropriate means of treatment.