Circulating microRNA as a diagnostic marker in populations with type 2 diabetes mellitus and diabetic complications

Diabetes mellitus (DM) is a global health care issue resulting from hyperglycemia-mediated life-threatening complications. Although the use of glucose-lowering agents is routinely practiced, high dependence on medication leads to poor quality of life for DM patients. While it is still not feasible to precisely determine the critical timing when DM is truly established, perhaps the best way to reduce DM-associated mortality is to prevent it. To this end, an exploration of prognostic molecules sensitive enough to detect early physiological alteration at the initiating stage would be required. Recently discovered small noncoding molecules, microRNAs (miRs), in body fluid seem promising to be utilized as a biomarker to monitor DM initiation and progression, as it is believed that expression of circulating miRs reflects disease pathology. Current DM-related miRs were often referred to miRs differentially expressed in insulin target organs (liver, muscle, and adipose tissues) or circulating blood (peripheral blood) in diabetic patients compared to their control counterparts, although these miRs could merely be resultant nucleotides from DM-induced organ impairment instead of the indicators of onset/progression of DM. In the current review, studies showing circulating miRs associated with type 2 DM and its complications are summarized, and future scope of using miRs as biomarkers for disease prognosis/diagnosis is also emphasized.