Bariatric Surgery and Diabetes Remission

Introduction

Bariatric surgeries were initially considered a “weight-loss surgery”; however, the surgery has much broader clinical advantages than just losing weight. One such benefit of bariatric surgery is the long-term remission of type 2 diabetes mellitus. Obese patients generally have insulin resistance, and if they also have dysfunctional beta-pancreatic cells, they are prone to developing type 2 diabetes mellitus. Bariatric surgery increases insulin sensitivity in these individuals resulting in diabetes remission for an extended period.

What Is Bariatric Surgery?

Bariatric surgeries are commonly known as “weight-loss surgery.” Therefore, surgical methods that help patients lose weight by altering their digestive systems are referred to as bariatric surgery. Gastric bypass, other weight loss surgeries, and other procedures can all be referred to as bariatric surgery. Therefore, bariatric surgery can be considered an umbrella term that covers gastric bypass surgery, sleeve gastrectomy, and several other weight loss surgeries. Bariatric surgeries are all fairly complex treatments, and they all work differently. Long-term weight loss is primarily achieved by changing the gastrointestinal hormone (gut hormone) levels. These hormones play a crucial role in inducing hunger and satiety. Alteration in the levels of these hormones leads to a new hormonal weight set point. Bariatric surgery is an alternative weight loss option for individuals who meet the necessary medical requirements and whose diet and exercise have failed to show a significant result.

Who Are Eligible for Bariatric Surgery and Who Are Not?

Individuals who can undergo bariatric surgery:

• Individuals with a body mass index (BMI) greater than or equal to 40. In addition, individuals who are at least 100 pounds overweight.

• Individuals who have obesity-related comorbidities like; heart disease, stroke, type 2 diabetes, hypertension (high blood pressure), etc.

• Patients who cannot achieve a significant result with exercise and diet and cannot achieve weight loss for a certain period.

Individuals who can not undergo bariatric surgery:

• Individuals with a medical history of blood clots, kidney stones, heart conditions, nutritional deficiencies, etc.

• Individuals suffering from mental health conditions like anxiety, depressive disorders, bipolar disorder, schizophrenia, etc.

• Individuals who have a history of eating disorders or substance abuse.

What Are the Types of Bariatric Surgery?

Some of the common types of bariatric surgeries are:

1. Gastric Bypass Surgery: Gastric bypass surgery is the most popular type of bariatric surgery. The process is divided into two steps. First, a tiny pouch separating the top of the stomach from the remainder of the stomach is formed. The first segment of the small intestine is then separated, and its lower end is joined to the newly formed tiny pouch in the stomach. Finally, the divided small intestine's top and bottom halves are joined. This leads to alterations in the food stream and gut hormones. This method works by limiting the amount of food the stomach holds and reducing calorie and nutrition absorption.

2. Sleeve Gastrectomy: About 80 % of the stomach is removed during this procedure. A tube-shaped pouch is left. The stomach is no longer able to hold food. The hormone ghrelin, which controls appetite, is reduced.

3. Gastric Band: An inflatable band is placed around the top of the stomach as part of the adjustable gastric band, resulting in a smaller pouch above. As a result, the patients feel full more quickly, and less food can be stored.

4. Duodenal Switch: In this technique, a pouch is made from a part of the stomach. The small intestine is mostly bypassed. This limits the amount of food the stomach can hold and accelerates the process of feeling full. As a result, the absorption of nutrients is decreased.

Why Is a Bariatric Surgery Done?

Bariatric surgery is done in the case of:

• Severely obese patients who are unable to lose weight through exercise and diet.

• Heart diseases.

• Stroke.

• Type 2 diabetes mellitus.

• Nonalcoholic fatty liver diseases.

• Sleep apnea (sleep disorder in which breathing starts and stops repeatedly).

What Is the Relation Between Obesity and Type 2 Diabetes Mellitus?

• Obesity has been associated with developing type 2 diabetes mellitus through insulin resistance. Various mechanisms have been proposed to prove the same, and one of the such mechanisms involves the increased release of several factors. These factors include; (NEFAs) non-esterified fatty acids, glycerol, leptin, adiponectin, etc. These factors are released from adipose tissues (abundantly found in obese people). This, in turn, results in insulin resistance.

• Even though this causes insulin resistance, not all obese patients will eventually develop type 2 diabetes mellitus since they can overcome it by increasing the amount of insulin released by pancreatic beta cells to compensate for the loss of insulin sensitivity. Therefore obese patients with beta cell dysfunction are prone to type 2 diabetes mellitus because of reduced insulin sensitivity and decreased pancreatic beta cell function.

How Does Bariatric Surgery Lead to Diabetes Remission?

Mechanism of type 2 diabetes mellitus remission after bariatric surgery:

1. Weight Loss: Although the precise mechanism for type 2 diabetes mellitus remission after bariatric surgery is still unclear, various hypotheses have been put forth. Reduced calorie intake results in significant weight loss and subsequently enhanced glucose sensitivity as one such mechanism. This was supposed to be accomplished through the bariatric surgery's malabsorptive and/or restrictive qualities. However, this does not explain some of the dramatic glycemic control changes observed right after surgery; thus, most glucose-lowering is done before weight reduction.

2. Insulin Sensitivity: A large reduction in insulin resistance fairly soon after bariatric surgery is one of the most crucial factors contributing to increased glucose tolerance and insulin sensitivity. When assessed using a homeostatic model assessment of insulin resistance, it has been found that insulin resistance drops by around 50 % in the first week after surgery and approaches a normal range. In addition, improvements in liver insulin sensitivity are noticed, and an increase in insulin clearance is assumed to result from a reduction in caloric intake.

3. Foregut or Hindgut Hypothesis: The foregut-hindgut theory implies that a greater amount of partially digested food is supplied to the distal intestine because the foregut is bypassed. In turn, this activates specialized L cells that help release peptide YY and glucagon-like peptide-1, both of which have been linked to weight loss. Furthermore, both positively impact pancreatic cells, increasing insulin sensitivity.

4. Bile Acids: Following bariatric surgery, circulating bile acid levels rise and are associated with enhanced glucose sensitivity. This is believed to happen due to a decreased mixing of partially digested nutrients and bile acids after surgery, which raises the concentration of free-circulating bile acids. As a result, the amount of glucose produced by the liver and the amount of gluconeogenesis (the process of conversion of non-carbohydrate substrate into glucose) in the portions of the gut without bile acids are both decreased.

What Is the Efficiency of Bariatric Surgery in Diabetes Remission?

• Recent evidence points to bariatric surgery as the most potent treatment for obesity, offering noticeably greater rates of T2DM improvement or remission.

• In addition to improving hypertension and dyslipidemia, bariatric surgery is linked to improvements or remission of diabetes in up to 80 % of cases and a reduction in incidental diabetes by 73 % of the cases.

• According to a recent Danish study, up to seven out of ten people with type 2 diabetes can undergo gastric bypass and have long-term diabetes remission.

• Type 2 diabetes may not permanently be cured by surgery. Some individuals who have remission and seem cured of the condition may relapse and resume having symptoms.

• However, some research also found a nearly 50 % decrease in microvascular complications (kidney diseases, nerve damage, and vision issues) following gastric bypass surgery.

Conclusion

Although bariatric surgery was initially thought of as a surgical weight-loss procedure, it has considerably impacted lowering rates of type 2 diabetes mellitus, improving cardiovascular health, and decreasing morbidity and mortality. Type 2 diabetes can be safely and effectively treated with bariatric surgery in obese patients. Before any significant weight reduction, the effects can be observed quickly, demonstrating the interaction of hormonal factors that increase insulin sensitivity by activating pancreatic beta cells. Although bariatric surgeries provide long-term remission of diabetes, the condition and its symptoms can relapse.