Although most such studies were conducted in at least one of the following conditions, relatively small, selected patient populations, either gender alone, or without adjustment for confounding factors [15–18, 20, 24–26], gender-specific associations have been reported in a large population-based study, where although inverse associations between serum PRL levels and type 2 diabetes mellitus were found in both genders, a significant trend for higher serum PRL levels with decreasing number of metabolic syndrome components was found in women but not in men [22]. Here, PRL is linked to diabetes mellitus.