Obesity is the most common metabolic disease nowadays. According to the World Health Organization (WHO) it is now reaching an epidemic size, and is the biggest health problem in developed and developing countries. WHO estimates that in 2008 there were 200 million of obese men and 300 million obese women all over the world, and 2-3 times as many were overweight. At the end of 2009 more than 45% men in Poland were overweight and 17% of them were obese (1). Among women the figures reached 30 and 15% respectively (2). Obesity, especially abdominal one, is known to contribute to the development of many metabolic disorders and diseases, including type 2 diabetes. About half of diabetics are thought to be obese (3). Nearly 350 million people are suffering from diabetes currently. In Poland, as is evidenced by NATPOL (III) research, 6-8% of the adult population are affected (4).

Standard procedures, regularly updated by the diabetics associations, invariably involve primarily the modification of lifestyle, and secondly a pharmacological treatment using one (metformin) or more drugs, including insulin (5, 6). Although weight reduction is an essential element of the therapy, experience shows that it is often difficult to obtain. This results on the one hand from a limited effectiveness of the methods and on the other one from the patients reluctance to maintain the rigorous diet and physical activity, especially long-term ones. This is why less than half the patients obtain the therapeutic aims (7).

An effective method of significant weight reduction, known for dozens of year, is bariatric surgery. The first attempts of jejunum-to-ileum or colon anastomosis and DeWind and Payne’s intestinal exemption treatment were made in 1950-60. In 1971 the first gastroplasty was performed, while the years 1970-80 brought on a vertical division of the upper part of the stomach and securing the channel along the lesser curvature with grid (vertical banded gastroplasty – VBG) or drain (silastic ring vertical gastroplasty – SRVG). The 1980s were marked of adjustable clamps. In the next years the operating techniques were developed and modified until the ones known now. A real breakthrough was the introduction of laparoscopic technique in the 1990s; it is now widely used in bariatric surgery (8-10).

For about 20 years the beneficial metabolic effects of body mass surgery have been highlighted (11). Currently there is abundant evidence that this treatment causes a rapid, substantial and long-lasting improvement in glycemic control in patients with type 2 diabetes (12-14). For this reason the term of metabolic surgery has come into use, although the concept was already considered at the end of 1970s. Metabolic surgery is defined as a surgical technique that modifies the digestive tract so that the change in the passage of food results in improving glycemic control in diabetes as a result of launching some mechanisms independent of weight reduction. Thus, the first purpose of metabolic surgery is not a weight reduction, but metabolic improvement.

A high effectiveness combined with lower perioperative complications risk resulted in a rapid growth in the number of operations performed worldwide. In 2013 179,000 such procedures were performed in the US (15). In the years 1993-2006 in Poland 2,584 such operations were made (16), and currently about 1,500 are performed annually. Current indications for the procedure, as defined in the recommendations by the Polish Association for the Study of Obesity, include severe obesity (BMI ≥ 40 kg/m²) or II° obesity (BMI = 35 to 39.9 kg/m²) with associated diseases, whose course can improve following a surgery, such as type 2 diabetes and other metabolic disorders, cardiovascular diseases, respiratory, bone and joint problems as well as severe psychological problems among people aged 18 to 60 (17). Similar criteria have been determined by other scientific societies, e.g. European Society for Endoscopic Surgery (EAES), the American Gastroenterological Association (AGA) or the American Society of Cardiology (AHA). Recently International Diabetes Federation (IDF) recommends considering an operation also for people with BMI 30-35 kg² with poorly controlled type 2 diabetes despite optimal pharmacological treatment, especially with an increased cardiovascular risk. Contraindications for the surgery include lack of earlier attempts at conservative treatment, inability to observe recovery, not stabilized mental illness and emotional disorders, alcoholism, drug addiction, lack of support from family or caregivers.

The bariatric operations currently performed can be divided into restrictive, i.e. those which limit the amount of food consumed, or reducing absorption (exempting, malabsorption) or restrictive-excluding, so those which combine the two previous techniques. The first are technically easier to perform, shorter and less aggravating for the patient. Exempting treatment results in a greater loss of body weight and is more effective, though it increases the risk of malnutrition. There are many surgical methods, which, as has been mentioned before, are constantly refined and developed, but in practice the most common ones include:

– laparoscopic adjustable gastric binding (LAGB),

– sleeve gastrectomy (SG),

– Roux-an-Y Gastric Bypass (RYGB).

A modification of the last one, which disconnects a larger section of the digestive tract, is the co-called Scopinaro procedure, i.e. BPD: bilio-pancreatic diversion or its variant, BPD-DS: bilio-pancreatic diversion-duodenal switch.

Adjustable gastric band is a very common procedure (46% of all bariatric surgeries in 2010) (18), due to positive results with a favorable safety profile, as demonstrated in many studies. Perioperative mortality for this method is < 0.1% within 30 days (19). The treatment is fully reversible and causes low nutritional deficits. For these reasons in 2011 American food and Drug Agency (FDA) allowed its application for patients with BMI of 30-35 kg/m², who also suffer from obesity-dependent diseases. Disadvantages of this method include the need of strict dietary control, possible vomiting, a possibility that the clamp can move or grow into the wall of the stomach. Less than 25% of the patients maintain good results after 14 years of observation, and 68% require repetition of surgery.

The most frequently performed operation in the world today is sleeve gastrectomy. In 2013, this surgery accounted for 42% of all bariatric surgeries in the United States (15). It involves removing a vast majority of the stomach and leaving only a small part along the lesser curvature. The advantages of such operations include a significant reduction in the capacity of the stomach and the removal of the ghrelin-producing part with a subsequent significant decline in its concentration and a growing concentration of YY (PYY) peptide. The disadvantage is a long anastomosis line and a possibility of a leak.

Another frequently performed procedure, although much more invasive, is Roux-en-Y gastric bypass. While the two previous techniques might be considered restrictive, RYGB is a mixed type, and as such it limits absorption. In 2013 it accounted for 34% of all bariatric surgeries carried out in the United States (15). The procedure consists in transecting with staplers a part of cardia area of approx. 20 ml capacity, which is then connected by anostomosis with a selected loop of the small intestine. This excludes the remaining part of the stomach, duodenum and the initial 60-100-cm section of the jejunum. The proximal end of the small intestine, formed after the resection, is connected end-to-side with a further intestinal loop, just about 100 cm from the stomach body and it is only at this point that the food mixes with pancreas enzymes and bile, which enables efficient digestion and absorption. The advantages of this method are: a significant reduction in the amount of food received and reversibility. The disadvantages include possible band breaking, blockade between the intestines and stomach, the need to comply with a diet and vitamin supplementation for the rest of patient’s life. RYGB can be considered the “gold standard” of the bariatric surgeries. For over 40% patients operated in this way remission of diabetes was reported and 69% do not use medication even after 3 years of the procedure (for the sleeve gastrectomy the figure was 43%). Complications associated with Roux-en-Y are about 4-5%, the mortality rate is 0.2%, and embolism (pulmonary and venous) 0.4%. Only 3-5% of the patients require reoperation.

Generally it is believed that, regardless of type, such operations should be performed by experienced surgeons in the centers evaluated by independent monitoring organizations. Clinical studies indicate that bariatric treatment in patients with type 2 diabetes lead to a significant reduction in body weight, and considerably improve glycemic control and metabolic rates.