Long-term Protective Changes in Adipose Tissue After Gastric Bypass.

<bold>Objective: </bold>Although long-term weight regain may occur after bariatric surgery, many patients are protected against relapse or development of type 2 diabetes. The study objective was to investigate whether this involves beneficial changes in adipose function.<bold>Research Design and Methods: </bold>Forty-nine obese women were investigated before and 2 and 5 years after Roux-en-Y gastric bypass (RYGB). At the 5-year follow-up, 30 subjects were pairwise matched for BMI and age to 30 control women. Clinical parameters and fine-needle biopsies from subcutaneous abdominal adipose tissue were obtained; fat cell size and number, lipolysis, adiponectin, and proinflammatory protein secretion were determined.<bold>Results: </bold>After 2 years, BMI decreased from 43 to 29 kg/m2, which was accompanied by improvements in insulin sensitivity (HOMA of insulin resistance [HOMA-IR]), increased circulating and adipose secreted adiponectin, and decreased adipose lipolysis and fat cell size but no change in adipocyte number. Between 2 and 5 years after surgery, BMI had increased to 31 kg/m2. This was associated with slightly increased HOMA-IR and unaltered circulating or adipose secreted adiponectin but higher secretion of tumor necrosis factor-α and increased lipolysis and number of fat cells but no change in adipocyte size. All these parameters, except lipolysis, were significantly more favorable compared with those in matched control subjects. Furthermore, the relationship between HOMA-IR and circulating adiponectin was less steep than in control subjects.<bold>Conclusions: </bold>RYGB improves long-term insulin sensitivity and adipose phenotypes beyond the control state despite weight regain. Postoperative beneficial alterations in adipose function may be involved in the diabetes-protective effect of bariatric surgery. [ABSTRACT FROM AUTHOR]