Metabolic surgery in the treatment of type 2 diabetes

Currently, there are no conservative treatments that can be used to cure type 2 diabetes. However, very high chances for a complete cure are given by metabolic surgery in the form of gastric and biliopancreatic shunting ^[1] . These operations are currently very widely used for the radical treatment of excess weight. As you know, in overweight patients, type 2 diabetes is very common as a comorbid pathology. It turned out that the implementation of such operations not only leads to normalization of weight, but also 80-98% of cases completely cure diabetes ^[2] . This fact served as the starting point for studies on the possibility of using such metabolic surgery for the radical treatment of type 2 diabetes in patients not only with obesity, but also with normal weight or in the presence of moderate excess body weight (with a BMI of 25-30) ^[3] .

Intensive studies are being conducted regarding the mechanism of action of metabolic surgery. Initially, it was assumed that weight loss is the leading mechanism in the normalization of glycemia. However, it turned out that the normalization of glycemia and glycated hemoglobin occurs almost immediately after gastric or biliopancreatic bypass surgery is performed, even before body weight begins to decrease ^[4] . This fact made us look for other explanations for the positive effect of the operation on metabolism. Currently, it is believed that the main mechanism of action of the operation is to turn off the duodenum from the passage of food. During gastric bypass surgery, food is sent directly to the ileum . The direct effect of food on the ileal mucosa leads to the secretion of glucagon-like peptide-1 (GLP-1), which refers to incretins . This peptide has a number of properties ^{[5] [6]} . It stimulates the production of insulin in the presence of elevated glucose levels. It stimulates the growth of beta cells in the pancreas (it is known that with type 2 diabetes there is an increased apoptosis of beta cells). Recovery of the beta cell pool is an extremely positive factor. GLP-1 blocks glucagon- stimulated glucose production in the liver. GLP-1 promotes a feeling of fullness by stimulating the arched nucleus of the hypothalamus .

Gastric bypass surgery has a history of more than 50 years. The positive effect of this type of metabolic surgery on the course of diabetes has been repeatedly confirmed by numerous clinical studies that have studied the long-term results of operations aimed at reducing excess body weight. It was shown that a complete cure for diabetes was observed in 85% of patients after gastric bypass surgery and in 98% after biliopancreatic bypass surgery. These patients were able to completely abandon any drug therapy. The remaining 2-15% showed significant positive dynamics in the form of a reduction in the dosage of antidiabetic drugs ^[2] . A study of long-term results showed that mortality from complications of diabetes mellitus in the group where gastric bypass surgery was performed was 92% lower than in the group where conservative treatment was performed ^[7] .

Clinical studies have been conducted in which the effect of metabolic surgery on type 2 diabetes was studied in patients with normal body weight and the presence of moderate excess body weight (with a BMI of up to 30) ^[8] . These studies fully duplicated the positive results of a 90% cure for type 2 diabetes in this category of patients and positive dynamics in the remaining 10%.

Similar results in the treatment of type 2 diabetes after gastric bypass surgery were obtained in adolescent patients ^[9]

If the body mass index of a patient with diabetes is 35 or higher, surgery is considered to be definitely indicated.

At the same time, when the situation concerns patients with normal or moderate increased body weight, it is necessary to assess the risks of surgery and those potential positive effects that can be obtained by curing diabetes. Considering the fact that even conducting competent conservative therapy is not a reliable prevention of diabetes complications (diabetic retinopathy , nephropathy , neuropathy and angiopathy with the whole spectrum of their serious consequences), the use of metabolic surgery may turn out to be a promising treatment method even in this group of patients with type 2 diabetes .

Currently, it is believed that surgery is indicated for a patient with type 2 diabetes in the presence of a BMI of less than 35, if he cannot achieve compensation for the course of the disease with oral drugs, and you have to resort to insulin. Since the leading mechanism of the disease in a patient with type 2 diabetes mellitus is insulin resistance, and not insulin deficiency, this appointment of additional exogenous insulin seems to be a strictly compulsory measure, not aimed at the cause of the disease. On the other hand, performing a shunt operation leads to the removal of insulin resistance simultaneously with the normalization of glycemia. For example, in Ballanthyne GH et al ^{[10], the} level of insulin resistance in patients before and after gastric bypass surgery was studied using the classical HOMA-IR method. It was shown that the level of HOMA before surgery averaged 4.4 and after gastric bypass surgery it decreased on average to 1.4, which is within the normal range.

The third group of indications is bypass surgery in patients with diabetes mellitus with a BMI of 23-35 who do not receive insulin. This group of patients is currently a research group. There are patients of normal or slightly elevated weight who want to solve the problem of their diabetes radically. They are included in such studies ^{[11] [12] [13]} . The results are very encouraging - a stable clinical and laboratory remission of diabetes in this group is achieved in all patients ^[14] .

• Intercurrent disease
• Functional surgery