Assoc Professor Harald Puhalla, MD FRACS
Assoc Professor Harald Puhalla, MD FRACS

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In Australia more than one million people are diagnosed with type 2 diabetes and at least two million have pre diabetes.

The rapid increase of type 2 diabetes goes in hand with the well-known obesity epidemic. A strong association in-between increased body fat and insulin resistance was initially described as part of the Syndrome X in the 1980’s. More recently in conjunction with hypertension and hyperlipidaemia, obesity and elevated glucose level were named metabolic syndrome. 80% of patients with type 2 diabetes are obese or overweight. When their diabetes becomes clinically apparent the risk for cardiovascular events rises sharply. In these patients obesity additionally increases their possibility of developing pulmonary embolism, cancer, osteoarthritis, depression or asthma.

The current management strategies of type 2 diabetes involves exercising, dieting, oral medication and/or insulin, but frequently the disease is slowly progressing and causes damage to a variety of organ systems. For decades researchers have tried to improve the treatment for type 2 diabetes and aimed to find a cure.

The gut hormones

Over the last few years it has become increasingly evident that the gastrointestinal tract plays an important role in energy regulation, and that gut hormones are involved in regulating the sugar metabolism. The gut hormones which significantly influence the glucose levels are GLP 1 (glucagon-like peptide-1), PYY (peptide YY) and grehlin. GLP-1 increases not only the insulin release in the pancreatic ß cells but also the sensitivity of the insulin receptors. PYY induces glycaemic control by early satiety and slowed down mouth to caecum transit time. Grehlin is also called the “hunger hormone” and if levels are low, appetite is decreased which reduces the urge to eat, therefore oral intake is small.

Bariatric operations can alter gut hormone expression

In a number of bariatric operations the bowel’s anatomy gets changed. This leads to the gut hormone levels being expressed differently and has a therapeutic effect on abnormal blood sugar levels. Depending on the specific type of bariatric procedure performed, surgery can lead to short and long term effects on Type 2 diabetes.

Some bariatric operations treat diabetes only as an effect of reducing the calorie intake by creating a small gastric pouch (gastric banding) which has shown to improve blood sugar levels. However the long-term results in maintaining the weight loss and glycaemic control were less convincing.

A gastric sleeve or gastric bypass achieve better long term results by not only having a small gastric pouch, but also activating the gut hormones much more effectively. A sleeve gastrectomy is where the greater curve of the stomach is removed. This leaves only 20% of the stomach as a narrow tube in-between the oesophagus and duodenum. A significant postoperative reduction in the hunger-hormone ghrelin occurs and this shows better long term results in regards to diabetes and weight loss compared to the laparoscopic gastric banding.

The procedure which showed even better long term results to cure type 2 diabetes is a gastric bypass, where a small gastric pouch (calorie restriction) is combined with a bypass of the proximal small bowel. This surgical concept has the advantage of additional nutritional malabsorption and further induces a strong gut hormonal response.

Different bypass procedures have been used to date. The Roux-en-Y gastric bypass has been around in different variations and is certainly a good operation. But performing it laparoscopically is demanding since it requires two gut-to-gut anastomosis. This complex surgery can lead to long operating times and higher complication rates. More recently the omega loop gastric bypass (also called mini-gastric-bypass or single anastomosis gastric bypass) has gained significant popularity due to its excellent outcomes combined with a much less sophisticated surgical technique resulting in a low complication rate.

The omega loop gastric bypass

The omega loop gastric bypass has a long narrow gastric pouch, which is connected to the jejunum and bypasses the proximal two meters of the small bowel.


Omega Loop Gastric Bypass

Omega loop gastric bypass: The postoperative food pathway is indicated as red dots and the pathway of the digestive juices (from pancreas, biliary and remnant stomach) are shown as green dots.   


After this operation, the oral intake (red dots) passes through the small gastric pouch and the anastomosis and enters the small bowel where the food mixes with the digestive juices from the pancreas, bile system and remnant stomach (green dots). Two important effects have been achieved: Firstly, the absorptive length of the small bowel is shortened. This causes a gentle malabsorption effect, adding an additional tool to losing weight in combination with the small gastric pouch. The second effect is the up-regulation of the hormones GLP1 and PYY caused by the distal entry of the nutrients into the small bowel. It is also presumed that the bypassed remnant stomach releases less of the hunger-hormone ghrelin.

Long term analysis shows that the omega loop gastric bypass is able to maintain excellent glycaemic control even beyond five years of the operation. The chance to remain off insulin is very high and only 16% require oral treatment. In comparison, patients five years after a sleeve gastrectomy, 62% are on oral diabetes medication and 8% require insulin. It has been shown that the gastric sleeve can be slowly “trained up” by ongoing or re-establishing wrong eating-habits (chronic over eating). Over the years the sleeve slowly dilates, the patient starts gaining weight and insulin resistance reoccurs.

An omega loop bypass is very effective in hyperglycaemia and established type 2 diabetes and also addresses obesity related comorbidities. Hypertension, hyperlipidaemia and sleep apnoea resolve in 90% of patients and osteoarthritis in more than 70%. This procedure may also help patients who have had poor results after a gastric band or sleeve gastrectomy to re-establish weight loss in the long term.

Some concerns have been raised that the malabsorptive component of a gastric bypass can cause vitamin or micro-nutrients deficiencies. All patients undergoing bariatric surgery should be investigated for pre-existing nutritional deficiencies before their procedure. This allows them to be treated in a timely manner. During the operation the length of the remaining “absorbing” small bowel in between anastomosis and caecum should be measured and be at least 3.5 meters. Daily multivitamin tablets after surgery help to prevent deficiencies. Further, a holistic treatment approach involving an experienced dietitian and a psychologist in the evaluation and postoperative management has shown superior long term outcome. However, patients should also be encouraged for a regular follow up with their GP or specialist where issues can be addressed early. Symptomatic deficiencies after an omega loop bypass are very rare and if necessary the operation can be reversed leaving a normal stomach and bowel anatomy.

The omega loop gastric bypass is an interesting treatment option for surgically fit people to cure their type 2 diabetes. Especially with its ability to activate specific gut hormones without relying only on a restricted oral intake, and in combination with a low complication rate. In conjunction with the resolving obesity related comorbidities this operation is able to maintain a good and healthy quality of life in the long term.