DRD2 and Parkinson disease: Bromocriptine is a dopamine D2 receptor agonist suppressing the production of prolactin and was originally used for treating hyperprolactinemia, Parkinson's disease, and so on.[24] Interestingly, bromocriptine was approved by the FDA for treating T2DM in 2009.[35] With the present data, the therapeutic effects of bromocriptine on hyperglycemia are independent of the known mechanisms, such as prolactin, MC4R, or circadian rhythms.[36] The precise mechanisms underlying the antidiabetic effects of bromocriptine remain unclear.