title: Improvements in insulin sensitivity and beta-cell function (HOMA) with weight loss in the severely obese. Homeostatic model assessment.
abstract: OBJECTIVE
  To examine the effect of weight loss on insulin sensitivity and beta-cell function in severely obese subjects of varying glycaemic control.
  
  
  METHODS
  Subjects were 254 (F:M 209:45) patients having adjustable gastric banding for severe obesity, with paired biochemical data from before operation and at 1-year follow up. The homeostatic model assessment method was used to calculate insulin sensitivity (HOMA%S) and beta-cell function (HOMA%B). Subjects were grouped by diabetic status and by pre-weight loss HbA1c.
  
  
  RESULTS
  Initial mean (sd) weight and body mass index were 128 (26) kg and 46.2 (7.7) kg/m2, respectively, and at 1-year were 101 (22) kg and 36.4 (6.7) kg/m2. The percentage of excess weight lost (%EWL) was 44.3 (14)%. HOMA%S improved from 37.5 (16)% presurgery to 62 (25)% (P < 0.001). %EWL was the only predictor of HOMA%S improvement (r = 0.28, P < 0.001). Subjects with normal fasting glucose, impaired fasting glucose and Type 2 diabetes had a fall, no change and increase in HOMA%B, respectively. The improvement in HOMA%B in subjects with diabetes (n = 39) was inversely related to the time with diabetes (r = -0.36, P = 0.02). In non-diabetic subjects the HOMA%S-HOMA%B relationship was favourably altered with weight loss, so that for any given HOMA%S there was an increase in HOMA%B (f = 11.8, P = 0.001). This improvement in HOMA%B was positively related to %EWL (r = 0.25, P = 0.019).
  
  
  CONCLUSIONS
  There are beneficial changes in both insulin sensitivity and beta-cell function with weight loss. Modern laparoscopic obesity surgery may have an important early role in the management of Type 2 diabetes in obese subjects.
authors.affiliation: Monash University Department of Surgery, Alfred Hospital, Melbourne, Victoria, Australia. john.dixon@med.monash.edu.au
authors.forename: J B
authors.initials: JB
authors.lastname: Dixon
authors.forename: A F
authors.initials: AF
authors.lastname: Dixon
authors.forename: P E
authors.initials: PE
authors.lastname: O'Brien
mesh_terms: D000328:Adult; D003920:Diabetes Mellitus / Q000517:prevention & control*; D005260:Female; D006706:Homeostasis; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D007515:Islets of Langerhans / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity; D009767:Obesity, Morbid / Q000378:metabolism* / Q000601:surgery; D016896:Treatment Outcome; D015431:Weight Loss / Q000502:physiology*