Omentectomy for Treatment of Diabetes Mellitus Type 2

Clinical studies have shown that central obesity is one of the strongest associations with Type II diabetes. Measurement of waist circumference at Vanderbilt was one of the most effective clinical measures of presence of type II diabetes and response to gastric bypass in a recent study. This central obesity points to the omentum as one of the major culprits for development and perpetuation of type II diabetes in humans. [1]

Animal studies at Vanderbilt have shown in normal size dogs that surgical removal of the visceral fat (Omentectomy):

• Decreases basal hepatic glucose production by nearly 40%
• Results in decreased FFA delivery to the liver
• Increases glucose utilization by peripheral insulin dependent tissues, predominantly skeletal muscle. [2] The animal studies were started to pursue the positive results seen by Swedish investigators who randomized 50 patients to either gastric banding or to gastric banding with omentectomy. At 2 years both groups had statistically similar weight loss but the patients in the omentectomy group had 2 to 3 times the improvements in oral glucose tolerance, insulin sensitivity and fasting plasma glucose as compared to control subjects. [3] They concluded that omentectomy, when combined with gastric banding in morbidly obese patients had a significant positive effects on the glucose and insulin metabolism.

Why does the removal of visceral fat (a very small percentage of the animal's weight) cause a 40% increase in peripheral glucose metabolism? The omentum is known to be a repository for macrophages and the increase in macrophage numbers is proportional to the increase in adiposity in humans. Both macrophages and adipocytes produce adipokines and cytokines that are known to influence glucose and insulin metabolism. The omentum is also known to be the major contributor of Free Fatty Acids into the portal circulation which adversely affects the hepatic insulin resistance.

Resection of the visceral fat which holds more numbers of the macrophages which in turn release the cytokines that preferentially disturb glucose metabolism should in theory then result in a marked improvement in glucose and fat metabolism.