Cross-sectional association between prolactin levels and non-alcoholic fatty liver disease in patients with type 2 diabetes mellitus: a retrospective analysis of patients from a single hospital in China

OBJECTIVE: This study aimed to retrospectively assess the association between prolactin (PRL) and non-alcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (T2DM). DESIGN AND SETTING: A retrospective, cross-sectional study was conducted at a single hospital in Anhui, China. PARTICIPANTS: A total of 406 patients with T2DM (230 men and 176 women) was included. OUTCOME MEASURES: P values for the independent t-test, the Mann-Whitney rank-sum test, the Spearman correlation analysis and multiple logistic regression models were used to explore the association between PRL and NAFLD in patients with T2DM. RESULTS: The results indicated that in both men and women, the levels of PRL were significantly lower in the T2DM with NAFLD group than in the T2DM without NAFLD group (men: 9.56 ng/mL vs 10.36 ng/mL, women: 10.38 ng/mL vs 12.97 ng/mL). In male patients, the levels of PRL were negatively correlated with hip circumference (r=−0.141, p=0.032), homoeostasis model assessment for insulin resistance (C-peptide) (r=−0.141, p=0.032) and triglyceride (TG) (r=−0.252, p=0.000) values and inversely correlated with high-density lipoprotein (r=0.147, p=0.025) levels. In female patients, PRL levels were negatively related to body mass index (r=−0.192, p=0.011), diastolic blood pressure (r=−0.220, p=0.003), waist circumference (r=−0.152, p=0.044), hip circumference (r=−0.157, p=0.037) and TG (r=−0.258, p=0.001) values. Logistic regression analysis revealed a negative relationship between PRL and NAFLD (men: OR 0.891, 95% CI 0.803 to 0.989, p=0.031; women: OR 0.874, 95% CI 0.797 to 0.957, p=0.004). As PRL levels increased, NAFLD prevalence decreased in both sexes (men: p=0.012, women: p=0.013). CONCLUSION: Our results suggest that low levels of PRL in the physiological range were markers of NAFLD in patients with T2DM and that PRL within the biologically high range may play a protective role in the pathogenesis of NAFLD.