Macroprolactinaemia in diabetic patients

OBJECTIVE: Prolactin levels have been shown to be reduced in poorly controlled diabetes mellitus; however, diabetic patients with high prolactin levels may be seen in clinical practice. The aim of this study was to evaluate diabetic patients with hyperprolactinemia, and to determine the role of macroprolactinaemia in these patients. MATERIALS AND METHODS: The study included 174 patients (153 women and 21 men) with hyperprolactinemia, retrospectively reviewed over a 2 years period. Data on presenting symptoms, the presence of diabetes mellitus, prolactin levels, macroprolactin levels, pituitary magnetic resonance imaging were collected in all patients. In addition; HbA1c, fasting blood glucose levels and postprandial glucose levels were collected in diabetic patients. RESULTS: Of the 174 patients, 27 were diagnosed with diabetes mellitus (15.5%). Eighteen of the diabetic patients with hyperprolactinaemia had macroprolactinaemia (66.6%). The prevalence of macroprolactinaemia in diabetic patients is higher than the non-diabetic population (66.6% vs. 39.5%, p=0.009). In diabetic patients with macroprolactinaemia, HbA1c levels were higher than the diabetic patients without macroprolactinaemia. CONCLUSION: The prevalence of macroprolactinaemia in diabetic patients was higher than the non-diabetic population. It seems necessary to determine macroprolactin levels in diabetic patients with hyperprolactinaemia; and in this case, further diagnostic evaluation is not warranted.