Glucose/galactose malabsorption is the most common form of diarrhea caused by genetic defects in newborns. Treatment includes dietary control, calcium and vitamin D supplementation. 1. Dietary control: The treatment of glucose/galactose malabsorption is mainly dietary control. Glucose and galactose intake should be avoided (including oral rehydration solution containing glucose), and fructose can be added to the diet to replenish energy and carbohydrates, and formula milk can be used for feeding. 2. Calcium and vitamin D supplementation: Calcium and vitamin D should be supplemented appropriately under the guidance of a doctor to reduce the risk of malnutrition. When newborns with genetic defects cause diarrhea, they should go to regular hospitals and improve the examination under the doctor’s guidance, and follow the doctor’s instructions for treatment.