The term metabolic surgery was first introduced in 1978 when Henry Buchwald and Richard Varco described it in their book "Metabolic Surgery" (9). This defined surgery performed on normal organs or systems to achieve a biological effect leading to health improvment. Although work on the surgical treatment of type 2 diabetes had been known previously (10), it was actually from the late 1970s that surgery began to establish itself as an effective method of reducing weight, improving quality of life and bringing about the resolution of many hitherto "incurable" diseases (including type 2 diabetes). In the present study, I evaluated the effectiveness and safety of surgical treatment of type 2 diabetes in the cases of patients with a BMI of 30–35 kg/ m2. For this purpose, we qualified patients for OAGB surgery. The first OAGB was performed by Robert Rutledge in 1997 and the results were published in 2001 (11). Since then, many papers (including randomised papers) have been published reporting the postoperative results of several thousand patients undergoing OAGB (12) and demonstrating the high efficacy and safety of this operation in its different variations (13, 14). In terms of type 2 diabetes resolution results, it is a comparable surgery to Roux-en-Y gastric bypass (RYGB), superior to restrictive bariatric surgery (15, 16). The lower incidence of complications after OAGB and the greater technical ease of performing the operation (11, 17) than RYGB are highlighted.
In papers published so far the results of surgery in patients with BMI < 35 kg/m2 are evaluated (18).
In one study, Lee and co-authors (19) evaluated the remission of type 2 diabetes after OAGB surgery among patients with a BMI < 35 kg/m2: fasting glucose levels returned to normal after 12 months among 89.5% of the operated patients, the presumed end points of type 2 diabetes treatment (HbA1C < 7.0%, LDL < 150 mg/dl and triglycerides < 150 mg/dl) were achieved by 76.5% of the operated patients.
In 2015, another paper appeared on the surgical treatment of patients with type 2 diabetes and a BMI of 30–35 kg/m2. Kular et al presented the results of 128 patients operated on at three Indian centres between 2007 and 2014 (20). They evaluated the recovery from diabetes (HbA1c < 6% without pharmacotherapy) after 1, 2 and 7 years. They found complete remission among 64, 66 and 53% of patients, respectively. The criteria for the diagnosis of obesity in patients of Asian origin are different from those in Europe (obesity of the first degree is a BMI of 27.5–32.4 kg/m2) the results of the work of both Kular and Lee are not directly applicable to the European population.
The latest guidelines of Society of American Gastrointestinal Endoscopic Surgery (SAGES) report the efficacy of surgical treatment of diabetes in a group with obesity of the first degree according to WHO (21).
In the vast majority of papers, the length of the excluded small bowel segment is 180–220 and is calculated according to the scheme proposed by Caballero et al (22).
Lee et al performed surgery on 286 patients (23). The patients were divided into three groups: 86 to the lower BMI group (BMI < 40, mean 36.0), 286 patients to the middle BMI (BMI 40–50, mean 43.2) and 72 patients to the higher BMI group (BMI > 50, mean 55.4). All procedures were performed laparoscopically. The average operation time was 130 minutes and the average hospital stay was 5.0 days. There were: 23 minor early complications (4.3%) and 13 major complications (2.0%), including one fatal complication (0.016%). There were no significant statistical differences in operation time and complication rates between groups. Exclusion length was 150 cm for the first group, 250 cm for the second group and 350 cm for the third group. The mean BMI reduction 2 years after surgery was 10.7, 15.5 and 23.3 for each group, respectively. Patients with BMI < 40 kg/m2 had more severe anaemia than patients in the other two groups. Patients operated on at the authors' centre did not have a diagnosis of type 2 diabetes (HbA1C 5.9–6.2%). In our work, we proposed the exclusion of 150 cm because of the lower risk of malnutrition; there will be papers in the literature about the exclusion of such a segment of intestine, but not in the treatment of type 2 diabetes in patients of the European population. This is part of the innovation of this work. Mahawar et al in their paper "Impact of biliopancreatic limb length on severe protein-calorie malnutrition requiring revisional surgery after one anastomosis (mini) gastric bypass" reported the results of 47364 operations performed by 118 surgeons from around the world (24). Overall, 0.37% (138/36,952) of patients required revision surgery due to malnutrition. The highest rate of 0.51% (120 / 23,277) was recorded for some patients at > 200 cm of excluded small bowel, and the lowest rate of 0% was observed at 150 cm.
To assess the effectiveness of this treatment, the change in HbA1c value and the change in dosage of medication are used. In our paper, the average HbA1c level before surgery was 8.45 ± 3.3% and 12 months after surgery it was 6.16 ± 0.96%, a decrease of 2.29 ± 3.3%. The remission rate of type 2 diabetes among patients with a BMI of 30–35 kg/m2 after metabolic exclusion and restriction surgery ranges from 50–100%. It depends on many factors, the most important of which are the type of surgery performed and the criteria adopted for disease remission. In his work, Busetto summarised the various definitions of remission. When defined as: fasting blood glucose (< 100 mg / dl), normal HbA1c (< 6%) and no need for diabetes medication, the frequency was 66.3% (25). In contrast, when HbA1c was < 7, up to 80.0% of patients met these criteria. Reis et al. report the highest proportion of remission of type 2 diabetes after OAGB (72.22%) and RouX-en-Y gastric bypass (70.43%) highlighting once again the incretin theory and the effect of the exclusion of the proximal small bowel on the improvement of glycemia after surgery (26). According to the accepted criteria, we found remission of type 2 diabetes among 14 patients (56%) and improvement among 6 (24%). Improvement among these patients meant complete discontinuation (n = 4, from 40 to 80 units of insulin) or reduction of insulin doses (n = 1, from 70 units to 5 units per day) and leaving oral hypoglycemic medication in place. Due to the place of residence of the patients (patients were from all over Poland), the modification of diabetes pharmacotherapy was the responsibility of family doctors/diabetologists in the place of residence. Despite maintenance of glycated haemoglobin < 6.2% (6.04–6.19%) among another three patients in this group, patients were maintained on oral hypoglycaemic medication (Glucophage XR). When asked by the attending physicians why the medication was not discontinued, they answered "just in case". This is due to a certain "fear" of complete withdrawal of medication in diabetics, even though laboratory tests indicated complete remission of the disease. Cummings et al. also noted this phenomenon (27). As highlighted in his paper, many physicians often leave patients on metformin therapy, even after normoglycaemia is achieved, using it to prevent relapse, with the hope of glycaemia-independent cardiovascular benefits or treatment of polycystic ovary syndrome. This practice contradicts any definition of diabetes remission, which requires patients to be off all antidiabetic medication. Unfortunately there is no developed standard in bariatric / metabolic research on how to deal with this problem.
Out of the study group, we found no improvement among 5 patients, according to the accepted criteria. Despite the lack of improvement, patients discontinued (even > 100 units of insulin per day) or significantly reduced daily doses. Despite not meeting the criteria for 'improvement', patients benefited significantly from weight reduction (%EWL > 80), reduced insulin doses and associated complications: hypoglycaemia, local reactions, post-insulin lipo-hypertrophy (28). Patients in this group, despite the declaration of willingness to cooperate in the postoperative period expressed during the qualifying visits, did not follow the dietary recommendations and did not have regular follow-up visits.
The average body weight of patients undergoing surgery in our centre was 97.1 ± 11.6 kg, and 12 months after surgery 73.8 ± 12.2 kg, meaning a reduction in average BMI from 33.5 ± 2 kg/m2 to 25.5 ± 2.5 kg/m2, respectively, %EWL 102.7 ± 38.5, these results are similar to those published in the literature to date and are unequivocally defined as a success of bariatric/metabolic surgery (29).
Wang et al. from October 2001 to October 2004 performed OAGB on 423 consecutive patients (87 men and 336 women) for morbid obesity (30). The average age of the patients was 30.8 years, preoperative average body weight 120.3 kg and average BMI 44.2 kg / m2. All operations were completed laparoscopically. BMI decreased from 44.2 to 29.2 at 12 months after surgery. The % EWL was 69.3%.
Among patients operated on in our Departament lipid parameters improved, from preoperative: total cholesterol 178.8 ± 42.2 mg%, HDL 37.9 ± 12.5 mg%, LDL 102.8 ± 39. 6mg%, Triglycerides 193.8 ± 66.1mg%, 12 months after surgery the values were: total cholesterol 167.2 ± 36.2 mg%, HDL 49.73 ± 13.76 mg%, LDL 92 ± 30.9mg%, Triglycerides 127.2 ± 72.55mg%.
In the meta-analysis "Metabolic effects of bariatric surgery in type 2 diabetic patients with body mass index < 35 kg/m2" Li et al. describe a decrease in triglycerides after bariatric surgery of 56.67 mg / dl, cholesterol of 48.38 mg/dl, and LDL of 36.7 mg/dl, and an increase in HDL of 5.37 mg/dl (31). In our study, the decrease in triglyceride values was much greater.
Statistical analysis of our patients' results showed that the change in HbA1c resulting from surgery is correlated with preoperative LDL values, these results are not confirmed by other authors. Milone et al. evaluated changes in the lipid profile of patients after sleeve gastrectomy and OAGB (32). At 12 months after surgery, the lipid profile as well as BMI and glycaemic control were better compared to baseline. Interestingly, these two surgical procedures were associated with completely comparable results at this time point, among patients after OAGB: % BMI showed a direct correlation with % TC and Δ% TG, but not with Δ % HDLc and % LDLc.
Complications are an important part of any surgical intervention. Among the patients undergoing OAGB in our centre there were no deaths, one conversion to open surgery occurred (0.04%), in one patient we found a wound infection in the postoperative period (0.04%), we did not find: anastomotic ulceration, anastomotic stenosis, staple line bleeding - complications described in previously published studies.
In their analysis, Yingjun et al. described the number of conversions (0.17%-1.23%) and the most common complications after OAGB, which include:
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early perioperative complications such as bleeding (0,2–2,5%), staple line leak (0,1%-2,1%) and wound infection (0,12%-1,1%)
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late complications, including reflux (0,9%-2,0%), anastomotic ulceration (0,6%-8%), and iron deficiency anaemia (4,9%-8,1%), which can be treated conservatively (77).
The perioperative mortality reported in this meta-analysis ranged from 0.08 to 0.18% (33).
Comparing these results, the incidence of complications among patients operated on at our centre is much lower both compared to OAGB and much more frequently performed in the world Roux-en-Y gastric bypass (33, 34).