Is it normal for a three-year-old child to still use diapers at night?
Generally, it is normal for a three-year-old child who has relatively poor development to still use diapers; however, if the child is developing well, continued diaper use may not be normal. The details are as follows:

If a child's development is slightly delayed and they have limited ability to control urination or bowel movements without experiencing any adverse reactions, it is normal for a three-year-old to still wear diapers at night. Since the maturity of the urinary system varies among individuals, some children may require more time to gain bladder control. In such cases, parents need not worry excessively and can gradually guide the child toward becoming diaper-free in daily life.
However, if a child is developing well and has good control over urination and bowel movements, but still frequently wets the bed at night and relies on diapers, this could indicate an abnormal condition. It might suggest poor bladder storage function or other underlying health issues such as urinary tract infections or kidney disorders.
In daily life, parents should ensure that the child gets adequate rest and sufficient sleep, maintain proper hygiene in the genital area, pay attention to the child's clothing, and avoid overly tight garments to prevent any negative impact on the child’s physical health.