Abnormal serum prolactin (PRL) levels, manifesting as either hyperprolactinemia (HPRL) or hypoprolactinemia, can disrupt glucose and lipid metabolic homeostasis. Pathological hyperprolactinemia (PRL＞100 μg/L) may lead to insulin resistance, impaired glucose tolerance, dyslipidemia, and an increased risk of atherosclerosis. In contrast, low serum PRL levels are associated with impaired pancreatic β-cell function, type 2 diabetes mellitus, visceral obesity, and nonalcoholic fatty liver disease. Transient hyperprolactinemia characterized by homeostatic functional increases (Homeostatic Functionally Increased Transient Prolactinemia, HomeoFIT-PRL) exerts protective metabolic effects and may enhance insulin sensitivity and glycemic control. Clinically, serum PRL levels should be closely monitored, and individualized intervention strategies should be developed for affected patients.