Larger omental adipocytes correlate with greater Fetuin-A reduction following sleeve gastrectomy

BACKGROUND: Shortly after bariatric surgery, insulin sensitivity improves and circulating Fetuin-A (FetA) declines. Elevated FetA may decrease insulin sensitivity by inhibiting insulin receptor autophosphorylation. FetA also mediates inflammation through toll-like receptor 4 and influences monocyte migration and macrophage polarization in the adipocyte. The role of dietary changes on FetA is unclear. It is also unknown whether changes in FetA are associated with adipocyte size, an indicator of insulin sensitivity. METHODS: Sleeve gastrectomy patients (n = 39) were evaluated prior to the preoperative diet, on the day of surgery (DOS) and six-weeks postoperatively. At each visit, diet records, anthropometrics and fasting blood were collected. Adipocyte diameter was measured in omental adipose collected during surgery. RESULTS: Although significant weight loss did not occur during the preoperative diet, HOMA-IR improved (p < 0.0001) and FetA decreased by 12% (p = 0.01). Six-weeks postoperatively, patients lost 9% of body weight (p = 0.02) and FetA decreased an additional 26% (p < 0.0001). HOMA-IR was unchanged during this time. Omental adipocyte size on DOS was not associated with preoperative changes in dietary intake, body composition or HOMA-IR. However, adipocyte size was strongly associated with both pre- (r = 0.41, p = 0.03) and postoperative (r = − 0.44, p = 0.02) change in FetA. CONCLUSION: FetA began to decrease during the preoperative diet. Greater FetA reduction during this time was associated with smaller adipocytes on DOS. Therefore, immediate, post-bariatric improvements in glucose homeostasis may be partly explained by dietary changes. The preoperative diet protocol significantly reduced insulin resistance, a modifiable risk factor for other non-bariatric procedures. Therefore, this dietary protocol may also be used preoperatively for procedures beyond bariatric surgery.