Obesity surgery: diabetes, overweight, risk factors and cardiovascular disease
Definition of obesity
Obesity is a disease that affects many people across large parts of the world. The World Health Organization (WHO) estimates that about 2 billion people suffer from the disease today. The prevalence of obesity (obesity) and overweight is greatest in the US. About two-thirds of all individuals living in the United States suffer from either overweight or obesity.
Overweight is defined as the body mass index (BMI, body mass index, weight in kilograms divided by the quadrant of individual height in meters) 25 kg/m2, obesity is defined as BMI 30 kg/m2 and severe (morbid) obesity corresponds to BMI 40 kg/m2. Epidemiological studies show that individuals with BMI 35 kg/m2 increase the strongest of all weight groups.
Obesity and overweight are associated with an increased risk of type 2 diabetes, metabolic syndrome and cardiovascular diseases. Recent studies that draw conclusions from observations among different populations, so-called observational studies, show that obesity and overweight are associated with several other age-related diseases that we have not known about before, such as cancer, joint disease (osteoarthritis), depression and possibly even dementia. Obesity also leads to the development and worsening of several risk factors that cause cardiovascular diseases, such as the metabolic syndrome, high blood pressure (hypertension), high blood lipidemia (hyperlipidemia), reduced insulin sensitivity (insulin resistance) and elevated levels of a particular type of blood lipids such as: called triglycerides (hypertriglyceridemia).1-3
Triglycerides are used by the body to store excess energy in our cells, especially in fat cells where they are then used as material to produce energy when the energy levels in the body are low. Elevated levels of triglycerides are associated with atherosclerosis of blood vessels.
Treatment for Obesity
The explosive increase in obesity and overweight has led to focused research to try to identify the underlying biological mechanisms that lead to the development of obesity. To date, it has not been possible to create a particularly effective drug treatment against obesity. Currently it is recommended that individuals with overweight, obese and also type 2 diabetes to exercise regularly. International guidelines recommend at least 150/min brisk walk every week, preferably 3.5 h/week.
Studies show that individuals who combine cardio training with resistance training experience greater improvements in blood sugar levels and, in addition, a stronger weight loss is noted, read more about the effects of physical activity for people with diabetes here. People with obesity or diabetes should also look after other lifestyle factors, such as eating habits, smoking and stress.
For those individuals who do not achieve satisfactory results from improved diet and increased exercise, there is the possibility of receiving additional medical treatment with Orlistat or Saxenda, however, these drugs are rarely used in clinical practice. The drug trials investigating the efficacy of Orlistat and Saxenda noted a meaningless weight loss, but in combination with low-calorie diet and increased physical activity, body weight decreases by 5 -10%.
However, these research reports showed that the study participants regained their previous body weight when they stopped taking the medicine. However, this is a recurring phenomenon in medical research for people with obesity, diabetes and cardiovascular diseases, often the body weight of the study participants returns to its former value.
In addition, the preparations have several serious side effects. The most successful medical treatment is obesity surgery, also known as obesity surgery or metabolic surgery.4
|Medication for Obesitas||Mechanism of action||Possible side effects|
|Orlistat (Xenical)||Reduced absorption of fat in the small intestine||Reduced absorption of fat-soluble vitamins, gastrointestinal spasms, increased flatulence, diarrhea, and fecal incontinence|
|Liraglutide (Saxenda)||Reduces gastric empty, increases feeling of satiety||Nausea, vomiting, inflammation in pancreas (pancreatitis)|
|Benzphetamine (Didrex)||Decreased appetite and increases feeling of satiety||Increases blood pressure, increased heart rate, more nervousness, insomnia, increased dry mouth and more frequent constipation|
|Diethylpropion (Tenuate)||Decreased appetite and increases feelings of satiety||Recurrent headaches, increased blood pressure, increased heart rate, more nervousness, insomnia, increased dry mouth and constipation|
|Lorcaserin (Belviq)||Decreased appetite and an increased feeling of satiety||Headache, dizziness, dry mouth, feeling tired and constipation|
|Phentermine and topiramate extended-release (Osymia)||Decreased appetite and an increased feeling of satiety||Insomnia, dry mouth, dizziness, constipation, tingling sensation in the skin, altered perception of taste and fragrance|
Obesity surgery, obesity surgery, obesity surgery, metabolic surgery, gastric bypass, bariatric surgery: dear child has many names
Obesity surgery involves surgical manipulation of the anatomy of the gastrointestinal tract, resulting in insufficient absorption of nutrients in relation to the energy levels that an individual with obesity needs. In addition, switching or shortening the anatomy of the small intestine leads to reduced secretion of hormones from our cells lining the gastrointestinal tract inside, these hormones affect our satiety, regulate body weight, energy balance, and the metabolism of bile acid. In addition, it has been noted that the bacterial flora of our intestines (microbiota) undergoes changes after obesity surgery.
Several studies have shown that obesity surgery results in dramatic and prolonged weight loss, improvement of metabolic functions, and in many cases remission of metabolic syndrome, type 2 diabetes and several cardiovascular risk factors. Studies have shown that the physiological changes leading to improved metabolism after obesity surgery are basically independent of the weight loss caused by the interventions.
Our gastrointestinal tract is the largest hormonal (endocrine) organ we have and it was through the discovery of hormones secreted from the gastrointestinal tract (gastrointenstinal hormones) that the area of Endocrinology (the doctrine of hormones) originally developed. Many of the gastro-intenstinal hormones have their influence on our brain where they regulate food lust but also signal that adjusts short-term and long-term energy reserves in the body.
Clinical trials have confirmed that obesity surgery is one of our most effective methods of treatment for individuals with obesity to reduce the risk of death, heart attack, stroke, type 2 diabetes, metabolic syndrome, cancer, other diseases and risk factors.
Obesity surgery, however, is not a completely risk-free intervention, obesity surgery is associated with several complications that occur during surgery but also long after surgery, this is one of the reasons why the procedure is indicated only in individuals with severe obesity or in individuals with obesity and high comorbidity. Research studies show that individuals with severe obesity are those who have the greatest benefit from obesity surgery.
Brief information about the structure and function of the gastrointestinal tract
The small intestine is divided into three structural parts. The first part is called the duodenum in medical language, this is a short structure measuring about 20 to 25 centimeters and is shaped like the letter C. The duodenum receives juices from the stomach and pancreas, and the liver (bile) these juices are, in fact, proteins (enzymes) that help to break down food into smaller structures to simplify the absorption of the future parts of the small intestine.
The digestive enzymes break down proteins, and bile emulsifies fat. The duodenum has one more task, namely to neutralize the juice from the stomach, and this does it by secreting a mucous alkaline solution that contains a lot of bicarbonate, and all this comes from specialized cells in the duodenum called Brunner’s glands.
The middle part of the small intestine is called the jejunum, it is about 2.5 meters long and has a special structure that makes its total area much larger than you think. In this part of the intestine, there are small cylindrical structure (villi in medical language), which allows absorbing more nutrition. In the jejunum, various products are absorbed into the blood, namely sugars, amino acids and fatty acids. The last part of the small intestine is called the ileum, it is about 3 meters in length and also contains villi similar to the jejunum. In this segment of the small intestine, vitamin B12 and bile acids are absorbed, as well as all other remaining nutrients. The ileum then proceeds to the large intestine.
Obesity surgical interventions are named after the anatomical change they make, hence it is helpful to know the names of these anatomical structures to understand what these operations intend to do with the body. A word that is often used is bypass, this simply means leading past a segment of the intestine of the body.
History and development of Obesitaskurgical methods of surgery
Surgical methods of treatment for obesity have been reported sparingly in the literature of the 20th century. In fact, surgical approaches were first accepted when the medical research community came to the insight into the growing obesity epidemic and the striking results of obesity surgery compared to other methods of treatment for obesity.
The first obesity surgery was performed in 1954 by Dr. Arnold Kremen and Dr. John Linner the procedure was named Jejuno-ileal bypass and the operation involves switching different segments of the small intestine so that the empty intestine (jejunum) and the ileum (ileum) are connected together, the operation entails an approximately 90% shortening of the small intestine. Initially, the idea of the procedure was to treat people with obesity who have at the same time a particular type of impaired blood lipidemia (dyslipidemia). The operation resulted in several severe complications and most patients experienced severe diarrhea, dehydration, vitamin deficiency, liver failure and severe joint inflammation (arthritis) due to the toxic overgrowth of bacteria remaining in the bypassed intestine. Several patients needed surgery due to complications from the procedure and therefore the operation has been abandoned.
In 1963, Dr. Henry Buchwald and Dr. Richard Varco showed that ileal bypass results in a sharp decrease in intestinal length which reduces the time for food to pass through the intestinal mucosa and thus reduced absorption of nutrients. Their surgical technique led to a decrease in blood lipids and the operation resulted in fewer side effects. After the ’70s, development was fast and several surgical methods were developed for the treatment of severe obesity, however, these methods were not accepted by the medical research community and new methods of surgery were developed in the 90s.
Nowadays, obesity surgery is divided into three categories; restrictive, malabsorptive or a combination of restrictive and malabsorptive surgery. This classification is based on our assumption that surgery techniques in obesity surgery either reduce food intake due to previous satiety or reduce the absorption of nutrients in the small intestine if shortened (bypass).
Restrictive surgical interventions are the most common surgical methods for severe obesity and the operations are to induce early saturation by lowering the volume of the stomach, some common restrictive surgery methods called Gastric bypass, Laparoscopic gastric strapping (LAGB) and Vertical Bandad gastroplasty (VBG).
Malabsorptive procedures reduce nutrient absorption by switching the intestinal connections so that the food is absorbed towards the end of the small intestine where the intestine passes into the colon, resulting in reduced nutrient uptake, an operation method that works in this way is called Biliopancreatic diversion (BPD). A fourth category would include other procedures such as temporomandibular surgery, abdominoplasty and liposuction, all of which cause weight loss.
Procedures such as Roux-en-Y gastric bypass (RYB) are one of the most common obesity surgery at present and are classified as a combination of restrictive and malabsorption surgery, the operation involves limiting the volume of the stomach and simultaneously bypassing the small intestine.
Another intervention called duodenal-jejunal bypass (DJB) involves a narrowing of the stomach and the interconnection of the earliest part of the duodenum to the cumin, the operation is becoming increasingly popular due to its ability to cause dramatic weight loss and improvement of blood sugar levels. RYGB, LAGB and BPD are the most common operative treatments for severe obesity
Studies estimate that more than 90% of all obese surgery are performed today via peephole surgery (laparoscopy) and this is probably one of the reasons why the risk of complications has been significantly reduced in recent years and that recovery is shorter than before.
Indications for obesity surgery: who should be operated?
Sweden follows the operating indications used internationally and introduced at a conference in the United States in 1991. Individuals with a body mass index of 40 kg/m2 who have tried lifestyle changes such as increased exercise and improved diet without significant results and individuals with BMI 35 kg/m2 who also have one or more obesity-related complications, such as type 2 diabetes, high blood pressure (hypertension), sleep apnea, lung diseases, fatty liver or elevated blood lipidemia (hyperlipidemia).
These guidelines were based on studies from 1980. Patients are advised to try treatment with increased exercise and better diet over a period to assess whether the patient could achieve satisfactory weight loss without surgery. Recent studies have shown that individuals with BMI 35 kg/m2 and one or more cardiovascular risk factors have a high risk of developing multiple chronic diseases, these individuals experience significant improvements in several risk factors and severe weight loss after undergoing obesity surgery.
Several researchers believe that people with BMI 35 kg/m2 and one or more risk factors should perform several serious attempts to lose weight with increased exercise and improved diet habits, but if the individual does not experience sufficient weight loss, obesity surgery should be an alternative.
The age limit for obesity surgery has been the same since the introduction of the interventions, in clinical practice, there is a strict upper age limit of 60 years. Some studies show that there are no reasons for such a sharp upper age limit. However, taking into account the risks associated with the operation as it grows, each physician should balance the expected effect on existing symptoms, disease and quality of life against the risks associated with surgery.
Results and experience from research
A comprehensive meta-analysis, which involves the merger of several clinical trials, shows that obesity surgery in severely obese individuals with type 2 diabetes leads to normalization or a sharp decrease in blood sugar levels (hemoglobin A1c, HbA1c), elevated blood lipidemia (hyperlipidemia) , high blood pressure (hypertension) and obstructive sleep apnea.
In more than three-quarters of patients undergoing obesity surgery, complete regression of type 2 diabetes is noted and half of those who did not get rid of their diabetes experienced a clinical improvement in their diabetes disease, which means that about 85% of all patients with diabetes experiencing clinical improvement after obesity surgia.4-6 Several other studies report similar results.7.8
In the well-known Swedish study called Swedish Obese Subjects (SOS), it was observed that after 2 years of follow-up, insulin levels that patients with diabetes needed to control their blood sugar decreased. The study noted that insulin levels decreased by 60% and long-term blood sugar decreased by 20% in subjects treated with obesity surgery,9 control group (the group compared to the intervention), i.e. those who did not undergo obesity surgery had a 3-fold increased risk of type 2 diabetes compared to with patients who underwent the operation.
Normalization of blood sugar levels in people with type 2 diabetes usually occurred a few days after surgery, sometimes even before the patient experienced a marked weight loss, surgery methods in the Swedish study were mainly Gastric bypass, Vertical banded gastroplasty and Gastric banding.4
The individuals who underwent surgery in the SOS study noted a clear weight loss rather shortly after surgery, but after a while, a slight weight gain was observed, the patients undergoing surgery still had significantly lower BMI 10 years after the procedure. The study also observed that people undergoing obesity surgery had a significantly reduced risk of premature death and other feared complications such as stroke and acute myocardial infarction. 5
A relatively recent American study has examined the effectiveness of treating individuals with uncontrolled type 2 diabetes and BMI 27 — 35 kg/m2 with obesity surgery and has followed patients for 5 years after surgery. The study showed that about a third of those who underwent Gastric bypass had improved blood sugar control, improved blood lipid levels and marked weight loss after 5 years.10
The study also showed that Roux-en-Y gastric bypass (RYB) surgery was most effective against cardiovascular risk factors and a large proportion of patients could end with daily insulin injections and tablet therapy for their diabetes after surgery, the other surgical methods were also very effective. The study showed that 45% of patients who underwent RYGB did not require insulin treatment afterward, compared to 25% of patients who underwent Sleeve gastroectomy, another restrictive method of treatment in obesity surgery.
Several organizations are considering recommending obesity surgery as a treatment for individuals with type 2 diabetes and a BMI between 30 — 30 kg/m2 (27.5 kg/m2 for East Asian patients) who do not experience enough results with medical treatment alone or lifestyle changes.11
Experimental research shows that obesity surgery performed in animals and people not suffering from obesity (BMI 30 kg/m2) still experiences positive effects on blood sugar levels even if it does not lose very much weight.2 A meta-analysis demonstrated that individuals with BMI 35 kg/m2 had equal major improvements in blood sugar levels in those individuals with BMI 35 kg/m2 who were operated.7
Other studies report that individuals with type 2 diabetes and BMI 29-30 kg/m2 undergoing malabsorption methods such as duodenal-jejunal bypass (DJB) developed normal blood sugar levels already 3 months after surgery and the majority completed their ongoing diabetes treatment. Thus, the level of blood sugar from obesity surgery does not appear to be strongly associated with the weight loss associated with the treatment.
In addition to improving blood sugar levels (HbA1c), obesity surgery also leads to improvements in other cardiovascular diseases, such as high blood lipidemia (hyperlipidemia) and high blood pressure (hypertension). Studies also show that mortality after obesity surgery decreases by 33-89% in the first 5 years, there is no medical treatment or lifestyle change that has a powerful effect as obesity surgery.
One study followed 7,925 patients treated with Roux-en-Y (RYGB) and compared with 7,925 people who were not treated with any obesity surgery, after 8.4 years of follow-up, it was found that patients treated with Roux-en-Y had 40% lower risk of death, 56% lower risk of cardiovascular disease. vascular diseases and 60% lower risk of cancer-related death compared to patients not treated with obesity surgery.8
Complications in Obesity Surgery
There is a common misconception that obesity surgery entails several serious complications that occur to a large extent, but the available studies show that this is not the case. A comprehensive meta-analysis including 361 studies and 84,048 patients showed that the risk of death within 30 days after surgery was 0.28% and the risk of death from 30 days up to 2 years after surgery was 0.35%,15 several other studies report that the risk of death due to Obesity surgery is around 0.25 -0.50%. This means that the risk of death as a direct consequence of the operation is incredibly low.
A comprehensive study in the US showed that patients who underwent Roux-en-Y gastric bypass (RYGB) or Laparoscopic Adjustable Gastric Band (LAGB) have a 30-day mortality of approximately 0.3% and only 4.1% of all patients undergoing obesity surgery in the study experienced at least one clinically significant Complication.16 This means that the risk of death in obesity surgery corresponds to the risk seen in ordinary abdominal operations.
Studies show that severe complications and death resulting from obesity surgery have declined sharply in recent years and these improvements are due to several factors including increased use of peephole surgery. 17
Complications due to obesity surgery vary from surgical material that makes trouble, for example, sometimes loosening the elastic bands at the LAGB and losing their attachment to the stomach muscle, which can cause tissue damage and stomach pain. In addition, complications occur due to the loss of attachment of the interconnection between the intestine (leakage), this can lead to bleeding, infections and tissue damage.
Some studies have shown that leakage from switches of the intestine at Roux-en-Y (RygB) is about 5 -7%. Gallstones are a common complication after obesity surgery, possibly due to rapid weight loss. Vitamin and mineral deficiency is also an occurring complication after obesity surgery and most often lifelong treatment with vitamin and mineral supplements is required. Individuals with mental illness should first undergo treatment for their mental illness and be mentally well-fed before undergoing obesity surgery as surgery may trigger new relapses.
Other common side effects include recurrent blood sugar drops (hypoglycemia) and a phenomenon known in English as “dumping syndrome” that occurs only in people who have undergone obesity surgery. Dumping syndrome is a complication that usually occurs after people who underwent obesity surgery eat a large meal or eat too fast. It can also be triggered by smaller amounts of food solid with high sugar value, such as sweets, chocolate, caramels, soft drinks and fruit juices. Symptoms usually occur 30-60 min after eating.
The most common symptoms are nausea, faintness, discomfort, dizziness, diarrhea, sweating and high heart rate. Sometimes the symptoms can occur one to three hours after food intake, in addition to these symptoms, the patient may suffer from blood sugar drop and in some cases loss of consciousness. Various tricks that can reduce the risk of dumping syndrome are to eat fewer meals, avoid drinking plenty of fluids during meals, consumption of food with fewer fast carbohydrates, chew food properly, avoid alcohol, many patients find it helpful if you lie down on your back after eating.
Dumping syndrome is due to the fact that a large amount of food quickly enters the intestine and causes a tension in the stomach or intestine (lower stomach), which causes a large exchange of fluid and other nutrients (macro particles) to move from the body’s bloodstream to the intestinal cavity.
When large amounts of food or liquid enter the stomach or intestines too quickly, these tissues expand rapidly and the rapid tension in the intestine leads to activation of the involuntary nervous system (autonomic nervous system). Activation of the nervous system strengthens many of them physiological reactions that give rise to the symptoms of “dumping syndrome”.
Food containing large amounts of sugar leads to a rapid increase in blood sugar levels and, as a defense, the secretion of larger amounts of insulin from the pancreas, which also leads to a fall in blood sugar, in addition, the sugar molecules attract large amounts of fluid from the bloodstream to the intestinal cavity which leads to fluid volume loss from the blood circulation of the body.
Metabolic improvements in Obesity Surgery
Obesity surgery has good effects on sugar metabolism and positively affects the body’s insulin secretion and sensitivity. Roux-en-y gastric bypass (RYB) is believed to improve metabolic functions in individuals with type 2 diabetes by enhancing insulin sensitivity and also enhancing beta-cell function (insulin-producing pancreatic cells), these positive physiological mechanisms have not been known to earlier.18
Studies also show that gastric bypass can lead to the revitalisation of pancreatic beta cells and sugar metabolism appears to be improved, beta cells become more sensitive to blood sugar levels and their ability to excrete insulin is also improved. The fact that the body’s beta cells develop a reduced sensitivity to blood sugar is common in type 2 diabetes, but many researchers think that the results also indicate that these disease processes are reversible.19 In addition, a larger release of glucagon-like peptide-1 (GLP-1) and incretins was noted from intestines, these are hormones that are released during food intake that regulate blood sugar levels.
|Metabolic improvements in Obesitasurgi7|
|Clinical improvements||Improvements for various interventions as a percentage (%)|
|Remissions of type 2 diabetes||48||84||98|
|Normalization of high blood pressure (hypertension)||43||68||83|
|Normalization of elevated blood lipids (hyperlipidemi)||59||97||99|
|Weight loss in procent (%)||47||62||70|
|Laparoscopic adjustable gastric strapping (LAGB), Roux-en-Y gastric bypass (RYB), Biliopancreatic diversion (BPD)|
Several metabolic improvements that occur after gastric bypass surgery are partly due to redesigned anatomy as this leads to disruption of hormone release from various hormone-secreting cells in the gastrointestinal tract and this leads to changes in insulin production and release. Some research groups show that the intestinal microflora is undergoing changes and that obesity surgery leads to the restoration of severe disorders of incretin released from the gastrointestinal tract. Incretin is a hormone that signals to our pancreas (pancreas) that the intestine contains energy-rich food and insulin is excreted as a result.
Studies have observed that a large proportion of patients undergoing obesity surgery return their type 2 diabetes many years after they were “cured” of the disease and did not have to take insulin or tablets daily. Of those who get rid of their type 2 diabetes return about 20 -30% of all patients type 2 diabetes. after 3-5 years. Studies have noted that a risk factor for recurrence of type 2 diabetes is a long duration of diabetes before surgery, which speaks for early intervention against obesity in type 2 diabetes. Patients with diabetes more than 5 years had 3.8 times increased risk of regaining their diabetes disease after 5 years compared to subjects with a duration of illness for less than 5 years.
Follow-up after Obesity Surgery
After surgery, the individual is usually sick for 2-7 weeks. A person is usually allowed to establish contact with a nutritionist, where he is recommended a liquid diet for 2-4 weeks, then a gradual transition to purees and normal diet, as well as multivitamin supplements (lime with vitamin D and Vitamin-B12), some also recommend iron and folacin therapy.
Several patients also receive acid regurgitation medicines and are offered treatment with proton pump inhibitors (PPI) in the first period after surgery, a large proportion of patients need lifelong treatment for acid regurgitation after obesity surgery. Appropriate weight loss is about 0.5-1.0 kg per week. After obesity surgery, it is very important that patients eat small portions and chew their food properly, this is due to the fact that the stomach, depending on which operation the patient underwent, can only cope with smaller amounts of food, about 2-2.5 deciliters.
It is important that the diet includes enough nutrition when portions are so small, therefore avoid fatty foods and fast carbohydrates, as well as eating often and regularly. After just over 2 weeks, the patient can slowly switch to a normal diet, i.e. meat, fish, pure and cooked food, this lasts for three weeks up to 1 month, after which patients can start eating a more rich fiber diet, raw food and whole grains. Most often it is recommended not to drink liquid while patients eat, be sure to drink before or after meals so that the stomach has time to take care of the liquid before ingestion.
After obesity surgery, patients have a lot of excess skin because patients lose a lot of weight. This may cause chapping, eczema and mobility problems, patients are offered to have this surgery, but should not gain or lose weight and should have a BMI below 30 kg/m2 or less.
- Bariatric Surgery. October 2004:1-15.
- Cohen R, Pinheiro JS, Correa JL, Schiavon CA. Laparoscopic Roux-en-Y gastric bypass for BMI <35 kg/m2: a tailored approach. Surgery for Obesity and Related Diseases. 2006;2(3):401-404. doi:10.1016/j.soard.2006.02.011.
- Thaler JP, Cummings DE. Minireview: Hormonal and metabolic mechanisms of diabetes remission after gastrointestinal surgery. Endocrinology. 2009;150(6):2518-2525. doi:10.1210/en.2009-0367.
- Sjöström L, Lindroos A-K, Peltonen M, et al. Lifestyle, diabetes, and cardiovascular risk factors 10 years after bariatric surgery. N Engl J Med. 2004;351(26):2683-2693. doi:10.1056/NEJMoa035622.
- Sjöström L, Peltonen M, Jacobson P, et al. Bariatric surgery and long-term cardiovascular events. JAMA. 2012;307(1):56-65. doi:10.1001/jama.2011.1914.
- Dixon JB, O’Brien PE, Playfair J, et al. Adjustable gastric banding and conventional therapy for type 2 diabetes: a randomized controlled trial. JAMA. 2008;299(3):316-323. doi:10.1001/jama.299.3.316.
- Buchwald H, Avidor Y, Braunwald E, et al. Bariatric surgery: a systematic review and meta-analysis. JAMA. 2004;292(14):1724-1737. doi:10.1001/jama.292.14.1724.
- Adams TD, Gress RE, Smith SC, et al. Long-term mortality after gastric bypass surgery. N Engl J Med. 2007;357(8):753-761. doi:10.1056/NEJMoa066603.
- Sjöström L, Narbro K, Sjöström CD, et al. Effects of bariatric surgery on mortality in Swedish obese subjects. N Engl J Med. 2007;357(8):741-752. doi:10.1056/NEJMoa066254.
- Schauer PR, Bhatt DL, Kirwan JP, et al. Bariatric Surgery versus Intensive Medical Therapy for Diabetes – 5-Year Outcomes. N Engl J Med. 2017;376(7):641-651. doi:10.1056/NEJMoa1600869.
- Rubino F, Nathan DM, Eckel RH, et al. Metabolic Surgery in the Treatment Algorithm for Type 2 Diabetes: A Joint Statement by International Diabetes Organizations. Diabetes Care. 2016;39(6):861-877. doi:10.2337/dc16-0236.
- Cohen RV, Schiavon CA, Pinheiro JS, Correa JL, Rubino F. Duodenal-jejunal bypass for the treatment of type 2 diabetes in patients with body mass index of 22–34 kg/m2: a report of 2 cases. Surgery for Obesity and Related Diseases. 2007;3(2):195-197. doi:10.1016/j.soard.2007.01.009.
- Christou NV, Sampalis JS, Liberman M, et al. Surgery Decreases Long-term Mortality, Morbidity, and Health Care Use in Morbidly Obese Patients. Annals of Surgery. 2004;240(3):416-424. doi:10.1097/01.sla.0000137343.63376.19.
- Perry CD, Hutter MM, Smith DB, Newhouse JP, McNeil BJ. Survival and Changes in Comorbidities After Bariatric Surgery. Annals of Surgery. 2008;247(1):21-27. doi:10.1097/SLA.0b013e318142cb4b.
- Buchwald H, Estok R, Fahrbach K, Banel D, Sledge I. Trends in mortality in bariatric surgery: A systematic review and meta-analysis. Surgery. 2007;142(4):621-635. doi:10.1016/j.surg.2007.07.018.
- Longitudinal Assessment of Bariatric Surgery (LABS) Consortium, Flum DR, Belle SH, et al. Perioperative safety in the longitudinal assessment of bariatric surgery. N Engl J Med. 2009;361(5):445-454. doi:10.1056/NEJMoa0901836.
- Nguyen NT, Hinojosa M, Fayad C, Varela E, Wilson SE. Use and outcomes of laparoscopic versus open gastric bypass at academic medical centers. J Am Coll Surg. 2007;205(2):248-255. doi:10.1016/j.jamcollsurg.2007.03.011.
- Mari A, Manco M, Guidone C, et al. Restoration of normal glucose tolerance in severely obese patients after bilio-pancreatic diversion: role of insulin sensitivity and beta cell function. Diabetologia. 2006;49(9):2136-2143. doi:10.1007/s00125-006-0337-x.
- Polyzogopoulou EV, Kalfarentzos F, Vagenakis AG, Alexandrides TK. Restoration of euglycemia and normal acute insulin response to glucose in obese subjects with type 2 diabetes following bariatric surgery. Diabetes. 2003;52(5):1098-1103.
- Lovshin JA, Drucker DJ. Incretin-based therapies for type 2 diabetes mellitus. Nat Rev Endocrinol. 2009;5(5):262-269. doi:10.1038/nrendo.2009.48.