Removing Omental Fat Does Not Improve Insulin Sensitivity

Surgical removal of visceral adipose tissue (VAT) in obese patients does not improve their metabolic function, according to a new study.

Researchers at Washington University School of Medicine (St. Louis, MO, USA), Vanderbilt University School of Medicine (Vanderbilt, Nashville, TN, USA), and IRCCS San Raffaele (Rome, Italy) conducted a 12-month randomized controlled trial to determine whether reduction in VAT by omentectomy in 22 obese subjects could enhance Roux-en-Y gastric bypass (RYGB) surgery-induced improvement in hepatic and skeletal muscle insulin sensitivity, and whether laparoscopic omentectomy alone in 7 obese subjects with type 2 diabetes mellitus (T2DM) improves insulin sensitivity. The greater omentum, weighing an average of 820 grams, was removed from subjects who had omentectomy in both studies.

The researchers found that in the first group of RYGB patients, after 12 months, muscle insulin sensitivity had roughly doubled and hepatic insulin sensitivity had increased about fourfold in both groups. There were no significant between-group differences. In the second study, after three months of follow-up, there was no effect on insulin sensitivity or use of diabetes medication. The study was published early online on May 10, 2010, in Gastroenterology.

"This study goes against the dogma that fat inside the belly [intra-abdominal fat] causes abnormal metabolism leading to type 2 diabetes,” said lead author Naji Abumrad, M.D. of Vanderbilt. "This is the first finding in humans that removing the belly fat on its own, or when combined with bariatric surgery, does not improve type 2 diabetes or insulin sensitivity in general.”

The greater omentum is a large fold of peritoneum that hangs down from the stomach, and extends from the stomach to the posterior abdominal wall after associating with the transverse colon. The common anatomical term, "epiploic” derives from the Greek "epipleein”, meaning to float or sail on, since the greater omentum appears to float on the surface of the intestines.

Related Links:
Washington University School of Medicine
Vanderbilt University School of Medicine
IRCCS San Raffaele