Adipokines as a therapeutic target by metformin to improve metabolic function: A systematic review of randomized controlled trials

Metformin is a widely used glucose-lowering drug, although its impact on adipose tissue function remains elusive. Adipose tissue-derived molecules regulate diverse physiological mechanisms, including energy metabolism, insulin sensitization, and inflammatory response. Alternatively, it has remained relevant to understand the therapeutic regulation of adipokines in efforts to alleviate inflammation in conditions associated with the metabolic syndrome. The current qualitative analysis of available literature focused on randomized clinical trials (RCTs) assessing the association between administration of metformin and adipokine regulation in individuals with metabolic syndrome. The major electronic databases such as MEDLINE, Cochrane Library, Scopus, and EMBASE were searched for eligible RCTs. Overall, 13 RCTs met the inclusion criteria, with a total of 4605 participants. Patients with metabolic syndrome were characterized by a state of obesity, impaired glucose tolerance, insulin resistance, and type 2 diabetes. Cumulative evidence from these RCTs supported the blood glucose lowering effects of metformin, in addition to promoting weight loss, ameliorating insulin resistance, and reducing pro-inflammatory markers such as interleukin-6 and tumor necrosis factor-α in patients with metabolic syndrome. Importantly, these therapeutic effects are associated with the upregulation of adiponectin and suppression of leptin and resistin.