Deranged metabolic profiles and insulin resistance (IR) have been documented in patients with prolactinomas. Few data are yet available on the apolipoprotein (apo) B/apoA-I ratio and its relationship with IR in patients with prolactinomas. This study was aimed to evaluate the level of apoB/apoA-I ratio and its association with IR in a Chinese subgroup with prolactinomas. Twenty-three prolactinoma patients and 20 healthy controls were enrolled in this study. The clinical anthropometric parameters and laboratory evaluation were collected. Insulin sensitivity was estimated using homeostatic model assessment [homeostasis model assessment of insulin resistance (HOMA-IR)]. Waist circumference and body weight index (BMI) were significantly higher in patients with prolactinomas than those in the controls (p < 0.05). Meanwhile, the prevalence of general and abdominal obesity seemed more pronounced in male patients compared to that in healthy subjects (57.14 vs. 0 % and 71.43 vs. 16.7 %, respectively). Furthermore, fasting glucose, insulin, HOMA-IR, triglyceride, and apoB/apoA-I ratio were also significantly higher in prolactinoma patients, but with lower level of apoA-I (p < 0.05). Univariate regression analysis revealed that prolactin, waist circumference, BMI, and presence of hypogonadism were significantly associated with IR (p < 0.05). However, only BMI [odds ratio (OR) = 1.937, 95 % confidence interval (CI) 1.112-3.375, p = 0.02] and prolactin (OR = 5.173, 95 % CI 1.073-24.94, p = 0.041) were shown to be independent predictors for the presence of IR in multivariate logistic analysis. This study confirmed the altered metabolic profile, including body weight gain, IR, disordered lipids, and apolipoproteins in prolactinoma patients. Prolactin and BMI were independently associated with IR. The effect of apoB/apoA-I ratio on IR is warranted to be determined in further studies.