Leptin centrally regulates body weight by linking nutritional status and neuroendocrine function.21 It is considered a proinflammatory adipokine: the binding to its receptor upregulates a number of signalling pathways, such as Janus kinase-2 (JAK-2)/signal transducer and activator of transcription-3 (STAT3).21 Leptin also stimulates the secretion of proinflammatory cytokines, such as TNF-α and IL-6; this process is associated with insulin resistance and type 2 diabetes.22 Here, STAT3 is linked to type 2 diabetes mellitus.