title: Type 1 Diabetes Mellitus and Bariatric Surgery: A Systematic Review and Meta-Analysis.
abstract: Type 1 diabetes mellitus (T1DM) has a rising global prevalence. Although it is vastly outnumbered by type 2 diabetes mellitus rates, it remains a persistent worldwide source of morbidity and mortality. Increasingly, its sufferers are afflicted by obesity and its complications. The objective of the study is to quantify the effects of bariatric surgery on T1DM by appraising the primary outcomes of glycosylated haemoglobin (HbA1c), insulin requirements and body mass index (BMI). Secondary outcomes included blood pressure, triglycerides and cholesterol biochemistry.
  
  
  
  A systematic review of studies reporting pre-operative and post-operative outcomes in T1DM patients undergoing bariatric surgery was done. Data were meta-analysed using random effects modelling. Subgroup analysis and quality scoring were assessed.
  
  
  
  Bariatric surgery in obese T1DM patients is associated with a significant reduction in insulin requirement (-48.95 units, 95 % CI of -56.27, -41.62), insulin requirement per kilogramme (-0.391, 95 % CI of -0.51, -0.27), HbA1c (-0.933, 95 % CI of -1.604, -0.262) and BMI (-11.04 kg/m(2), 95 % CI of -13.49, -8.59). Surgery is also associated with a statistically significant reduction in systolic and diastolic blood pressure and a significant beneficial rise in HDL. Heterogeneity in these results was high, and study quality was low overall.
  
  
  
  Bariatric surgery in obese T1DM patients is associated with a significant improvement in insulin requirement and a significant though modest effect on HbA1c. These early results require further substantiation with future studies focusing on higher levels of evidence. This may offer a deeper understanding of diabetogenesis and can contribute to better selection and stratification of diabetic patients for metabolic surgery and future metabolic treatment strategies.
authors.affiliation: Department of Surgery and Cancer, Imperial College London, 10th Floor, Queen Elizabeth the Queen Mother (QEQM) Building, Imperial College Healthcare NHS Trust at St Mary's Hospital, Praed Street, London, W2 1NY, UK. h.ashrafian@imperial.ac.uk.|Department of Bariatric Surgery, Chelsea and Westminster Hospital, London, UK. h.ashrafian@imperial.ac.uk.|Department of Hepato-pancreato-biliary (HPB) Surgery, Hammersmith Hospital, London, UK. h.ashrafian@imperial.ac.uk.
authors.forename: Hutan
authors.initials: H
authors.lastname: Ashrafian
authors.affiliation: Department of Surgery and Cancer, Imperial College London, 10th Floor, Queen Elizabeth the Queen Mother (QEQM) Building, Imperial College Healthcare NHS Trust at St Mary's Hospital, Praed Street, London, W2 1NY, UK.
authors.forename: Leanne
authors.initials: L
authors.lastname: Harling
authors.affiliation: Department of Surgery and Cancer, Imperial College London, 10th Floor, Queen Elizabeth the Queen Mother (QEQM) Building, Imperial College Healthcare NHS Trust at St Mary's Hospital, Praed Street, London, W2 1NY, UK.
authors.forename: Tania
authors.initials: T
authors.lastname: Toma
authors.affiliation: Department of Surgery and Cancer, Imperial College London, 10th Floor, Queen Elizabeth the Queen Mother (QEQM) Building, Imperial College Healthcare NHS Trust at St Mary's Hospital, Praed Street, London, W2 1NY, UK.
authors.forename: Christina
authors.initials: C
authors.lastname: Athanasiou
authors.affiliation: Department of Surgery, Athens University Medical School, Athens, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Nikiteas
authors.affiliation: Department of Surgery and Cancer, Imperial College London, 10th Floor, Queen Elizabeth the Queen Mother (QEQM) Building, Imperial College Healthcare NHS Trust at St Mary's Hospital, Praed Street, London, W2 1NY, UK.|Department of Bariatric Surgery, Chelsea and Westminster Hospital, London, UK.
authors.forename: Evangelos
authors.initials: E
authors.lastname: Efthimiou
authors.affiliation: Department of Surgery and Cancer, Imperial College London, 10th Floor, Queen Elizabeth the Queen Mother (QEQM) Building, Imperial College Healthcare NHS Trust at St Mary's Hospital, Praed Street, London, W2 1NY, UK.
authors.forename: Ara
authors.initials: A
authors.lastname: Darzi
authors.affiliation: Department of Surgery and Cancer, Imperial College London, 10th Floor, Queen Elizabeth the Queen Mother (QEQM) Building, Imperial College Healthcare NHS Trust at St Mary's Hospital, Praed Street, London, W2 1NY, UK.
authors.forename: Thanos
authors.initials: T
authors.lastname: Athanasiou
mesh_terms: D050110:Bariatric Surgery / Q000379:methods; D003922:Diabetes Mellitus, Type 1; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D009767:Obesity, Morbid / Q000601:surgery*
chemical_list: D006442:Glycated Hemoglobin
keywords: Bariatric surgery; Body mass index; Diabetes; Glycosylated haemoglobin; HbA1c; Intervention; Metabolic surgery; Surgery; Type 1 diabetes mellitus; Type 2 diabetes mellitus; Weight loss