title: Remission of type 2 diabetes mellitus following bariatric surgery: review of mechanisms and presentation of the concept of 'reversibility'.
abstract: OBJECTIVE
  Roux-en-Y gastric bypass (RYGB) leads to remission of type 2 diabetes mellitus (T2DM) in a majority of patients. This is prompting investigation of RYGB, and other bariatric operations as interventional therapies for T2DM.
  
  
  RESULTS
  The impact of RYGB is due to an increase in the release of gastrointestinal hormones in response to a meal [glucagon-like peptide, peptide YY, oxyntomodulin]. This effect involves the parasympathetic nervous system. These same hormones are responsible for an early increase in β-cell secretion of insulin, leading to early remission of T2DM following RYGB. Progressive weight loss leads to a later improvement in peripheral insulin sensitivity, which is required for later remissions, and is responsible for re-emergence of T2DM in individuals who regain weight in long-term follow-up. As the success of bariatric surgery has prompted the emergence of the concept that T2DM is reversible, we offer a theory to predict reversibility of diabetes after bariatric surgery that is based on baseline beta cell function.
  
  
  CONCLUSIONS
  This review will improve the understanding of the physiology of bariatric surgery and its impact on T2DM, stimulate investigations into new avenues to treat T2DM, and allow better selection of nonobese individuals for interventional therapy of T2DM.
authors.affiliation: Department of Surgery, University of Massachusetts Medical Center, Worcester, Massachusetts 01655-0333, USA. peruginr@ummhc.org
authors.forename: Richard A
authors.initials: RA
authors.lastname: Perugini
authors.forename: Samir
authors.initials: S
authors.lastname: Malkani
mesh_terms: D003920:Diabetes Mellitus / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D015390:Gastric Bypass; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism; D009765:Obesity / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome; D015431:Weight Loss
chemical_list: D007328:Insulin