Type 2 diabetes mellitus as a disorder of galanin resistance

The increasing prevalence of type 2 diabetes mellitus with its high morbidity and mortality becomes an important health problem. The multifactorial etiology of type 2 diabetes mellitus is relative to many gene and molecule alterations, and increased insulin resistance. Besides these, however, there are still other predisposing and risk factors accounting for type 2 diabetes mellitus not to be identified and recognized. Emerging evidence indicated that defects in galanin function played a crucial role in development of type 2 diabetes mellitus. Galanin homeostasis is tightly relative to insulin resistance and is regulated by blood glucose. Hyperglycemia, hyperinsulinism, enhanced plasma galanin levels and decreased galanin receptor activities are some of the characters of type 2 diabetes mellitus. The discrepancy between high insulin level and low glucose handling is named as insulin resistance. Similarly, the discrepancy between high galanin level and low glucose handling may be denominated as galanin resistance too. In this review, the characteristic milestones of type 2 diabetes mellitus were condensed as two analogical conceptual models, obesity-hyper-insulin-insulin resistance-type 2 diabetes mellitus and obesity-hyper-galanin-galanin resistance-type 2 diabetes mellitus. Both galanin resistance and insulin resistance are correlative with each other. Conceptualizing the etiology of type 2 diabetes mellitus as a disorder of galanin resistance may inspire a new concept to deepen our knowledge about pathogenesis of type 2 diabetes mellitus, eventually leading to novel preventive and therapeutic interventions for type 2 diabetes mellitus.