Adipocyte Size Threshold Matters: Link with Risk of Type 2 Diabetes and Improved Insulin Resistance After Gastric Bypass

Context: Adipocyte volume has been associated with insulin resistance and type 2 diabetes. Objective: Our purpose was to identify an adipocyte volume threshold linked with increased insulin resistance risk, and to examine its association with insulin resistance improvement after bariatric surgery. Setting and Design: We investigated two cohorts of Caucasian women, candidates for bariatric surgery, from two institutional centers in France (age 42.0 +/- 11.5 years; body mass index, 47.6 +/- 6.9 kg/m(2)) and Germany (age 41.3 +/- 11.2 years; body mass index, 49.5 +/- 8.1 kg/m(2)). 38% of the subjects had gastric bypass surgery and were followed for 6 months after the intervention. We defined a group of subjects with type 2 diabetes or at risk of type 2 diabetes (DRD) and investigated the relations between adipocyte volume and this status before and after surgery. Results: In both cohorts, subjects with DRD presented enlarged adipocytes (France, P = 3 x 10(-4); Germany, P = 3 x 10(-10)) and we were able to determine thresholds in each cohort above which diabetes risk was potentially increased (France: 1003 +/- 42 pL, Germany: 798 +/- 32 pL). Subjects above those adipocyte thresholds were less prone to disappearance of the DRD status after bypass surgery (France, risk ratio = 2.1, P = .024; Germany, risk ratio = 1.3, P = .05). Conclusions: We show in two cohorts of morbidly obese subjects that a specific adipocyte volume threshold may predict an increased risk for obesity-associated type 2 diabetes. However, this threshold might be established for each specific investigation site. Having a high adipocyte size is associated with a lower improvement of insulin resistance after bypass surgery in both cohorts.