Sex-specific differences in the relationship between prolactin and glucose metabolism in first-episode schizophrenia

BACKGROUND: Hyperprolactinemia and glucose dysregulation frequently co-occur in schizophrenia; however, their sex-specific interplay at illness onset remains poorly understood. We hypothesized that there was sex difference in abnormal glucose metabolism and prolactin (PRL) levels, as well as in their interaction, among patients with schizophrenia. This study aimed to examine sex differences in the interrelationship between PRL and glucose metabolism in first-episode schizophrenia patients. METHODS: One hundred and eighty-nine first-episode patients with schizophrenia were recruited. Fasting glucose, insulin, and PRL levels were determined in all patients. RESULTS: We found that 35.4% of male and 9.7% of female patients had PRL levels outside the normal range. Regarding glucose metabolism parameters, 57.3% of males and 48.4% of females exhibited insulin resistance. Additionally, PRL levels were lower and fasting insulin levels were higher in male patients than in female patients. Fasting glucose levels were negatively associated with PRL levels only in males (r =-0.21 , p =0.04 ), but not in females. Furthermore, regression analysis confirmed their association after adjusting for confounding factors in male patients (β= -0.20, p = 0.05). CONCLUSIONS: Our findings provide novel insights into sex differences in the interrelationship between glucose metabolism and PRL at the onset of schizophrenia. This study contributes to the growing evidence underscoring the importance of considering sex when investigating the molecular mechanisms and metabolic disturbances underlying schizophrenia.