Metabolic surgery as an intervention for the global epidemic of uncontrolled diabetes: a systematic review of the current evidence and future directions

Introduction

Diabetes mellitus type 2 (DMT2) continues to cause over 1.5 million deaths yearly (1,2). The exorbitant cost of insulin and medications has further led to difficulties for patients in obtaining treatment, resulting in approximately 4 million deaths each year from diabetic complications (3,4). Oral hypoglycemic drugs are associated with undesirable side effects such as syncope, ischemia, and renal impairment (5,6). Findings indicate that metabolic surgery (MS) can induce remission of DMT2 in numerous patients. The objective of our systematic review is to evaluate the effectiveness of MS in achieving DMT2 remission rate, duration, safety profile, and comparison of different types of MS procedures for remission. We present this article in accordance with the PRISMA reporting checklist (available at https://aos.amegroups.com/article/view/10.21037/aos-23-4/rc).

Methods

Inclusion/exclusion criteria

Peer-reviewed articles focusing on the middle-aged and older population published in English for 6 years from 2016 to 2022 were included. Only studies involving human participants directly relevant to the study question are deemed appropriate for inclusion. Studies published before the specified inclusion years, papers written in languages other than English, papers focused on the pediatric population, animal research, and papers irrelevant to the subject under study were excluded. These requirements have been established to guarantee that the chosen papers will support the study’s goals while maintaining the desired scope and concentration.

Information sources

Google Scholar and the PubMed database were used to gather evidence to support this systematic review of publications between 2016 and 2022. We extracted all important data demonstrating the safety and effectiveness of medical and surgical management of DMT2 using pertinent keywords and medical subject headings (MeSH). The keywords used were Oral hypoglycemics, Insulin, Diabetes Mellitus, and Gastric/Metabolic surgery. We used the Boolean scheme to jolt keywords with the MeSH strategy format and then implemented it in the PubMed database.

Search strategy

The keywords and MeSH search terms included “diabetes mellitus type 2”, “metabolic surgery”, “pharmacotherapy for diabetes mellitus type 2”, “bariatric surgery”, “complications of metabolic surgery”, and “efficacy of metabolic surgery”. The titles and abstracts of each article were studied to determine relevance to the review. After a thorough review of the articles, duplicates were eliminated. In our primary data collection, i.e., PubMed, we built MeSH concepts search builder & used the Boolean AND OR search technique.

Data collection process

We retrieved the articles for review and checked references carefully to avoid missing any important articles. We removed duplicate sources using Endnote. After screening titles and abstracts, we thoroughly checked full texts to ensure relevance and quality.

Study screening and quality appraisal

The first and second authors independently screened titles, abstracts, and full texts, with any disagreements resolved by the third author. All authors equally reviewed the final papers for quality and compiled data. We compared and contrasted data from the studies chosen to assess the potency of MS, evaluating parameters such as reduction in hemoglobin A1C (HbA1C) percentage, body mass index (BMI) and weight loss, remission of DMT2, postoperative complications, anemia development, end-organ complications reduction, mortality rate, and quality of life improvement. The following tools were used for the respective number of studies as in Table 1. Cochrane Risk of Bias Tool: using the modified Cochrane Collaboration tool to determine the bias risk in randomized controlled trials. The degree of bias is expressed as a rating (high, low, or unclear) for particular components. Only papers with a low bias risk were taken into consideration. Newcastle-Ottawa scale: the Newcastle-Ottawa scale classifies risk into three categories: high risk [0–3], moderate risk [4–6], and low risk [7–9]. Only modest and low-risk articles were included. Assessing the Methodological Quality of Systematic Reviews (AMSTAR) checklist: every article that matched at least 70% of the criteria was included.

Scale for the Assessment of Narrative Review Articles (SANRA) checklist: every article that matched at least 70% of the criteria was included.

Results

We searched for articles from 2016 to 2022 on PubMed, PubMed Central (PMC), and Google Scholar. Out of 18,406 articles found, only 119 met the eligibility criteria after screening for title, abstract, and specific inclusion/exclusion criteria. After analyzing the quality of the 40 articles, 31 were considered moderate to excellent quality, with an average standard of more than 80%. The PRISMA provides further details on the process (Figure 1).

Figure 1 Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram. **, PubMed Central.

The brief descriptions of all reviewed papers including authors’ information, the type and purpose of each study, and conclusions, are listed in Table 2.

Outcomes measured

Our analysis involved categorizing the data into several groups based on different criteria. These categories included articles that compared pharmacotherapy and one or more types of MS, studies that evaluated the relationship between BMI and choice of intervention, research examining various surgical procedures, and investigations on remission rates of DMT2 after surgery.

The primary focus of this study was to examine the effects of metabolic operations in reversing DMT2. This reversal was determined by evaluating parameters such as HbA1C, blood glucose levels, presence or absence of the need of pharmacotherapy after MS. We also studied reduction in body mass index and presence of postoperative complications, including anemia. The findings indicated that patients who achieved remission had fewer complications than those in the control group.

Our analysis further revealed a varying range of DMT2 remission rates ranging from 11.2% to 100%. Among the 31 studies reviewed, 14 favored Roux-en-Y gastric bypass (RYGB), one advocated sleeve gastrectomy (SG). At the same time, another suggested biliopancreatic diversion with duodenal switch as being superior in achieving better outcomes for patients with DMT2.

Overall, we found that surgical interventions are significantly more effective than lifestyle adjustments or treatment with metformin alone and/or other hypoglycemic agents. As described in Tables 3,4 (22,23), our systematic review found that four trials have found that anemia after RYGB or one-anastomosis gastric bypass (OAGB) was common, with rates ranging from 8% to 33%. Nine studies found that gastrointestinal hemorrhage happened between 1% and 10% of the time (36).

Discussion

DMT2 is a metabolic disorder characterized by elevated blood sugar levels resulting from impaired insulin function. The management of DMT2 often involves oral anti-diabetic medications; however, these medications have certain drawbacks, such as the risk of experiencing hypoglycemia, gastrointestinal issues, weight gain, an increased likelihood of cardiovascular events, and potential complications in renal and liver health. Furthermore, long-term utilization of specific oral antidiabetic medications may contribute to the development of insulin resistance, which can worsen glucose regulation, in addition to particular concern is the occurrence of hypoglycemia, which manifests through symptoms like dizziness, confusion, sweating, and loss of consciousness. Therefore, it is crucial to develop personalized treatment plans for individuals with DMT2 while closely monitoring their progress, which is where metabolic surgery can be incorporated. In addition, some drugs may elicit gastrointestinal problems and contribute to weight gain or cardiovascular incidents such as heart attacks or strokes, especially among those suffering from pre-existing cardiovascular diseases. Long-term usage also poses risks to kidney and liver functionalities and aggravation towards developing insulin resistance, resulting in further deterioration of glycemic control.

In our comprehensive systematic review, we analyzed a wide array of high-quality literature, encompassing randomized control trials (RCTs), letters to editors, consensus reviews, and statements. Our findings strongly indicate that a considerable proportion of patients undergoing MS experience remission of diabetes during the follow-up period. Therefore, incorporation of this procedure into diabetes management protocols is warranted, irrespective of the patient’s BMI category, whether they are overweight or obese. MS alters the digestive system to limit food intake and calorie absorption. In addition to that, studies have shown MS has the potential to improve insulin sensitivity, beta-cell function, and the gastrointestinal microbiome (35). Techniques include gastric bypass (GB), SG, and adjustable gastric banding (AGB) etc. According to a study published in the Lancet journal by Mingrone et al., the 10-year follow-up after MS showed DMT2 remission in 37.5% of patients (7). The reason why MS is more effective than other gastrointestinal procedures is unclear (8). Numerous studies have shown the proof of DMT2 remission and that glucagonlike peptide 1, gastric inhibitory peptide, ghrelin, fibroblast growth factor-19, bile acids, Insulin, glucagon, adiponectin, leptin, tumor necrosis factor-α, interleukin-6 play a role in this remission and relapse of diabetes after anatomical rearrangement (38).

Multiple studies have been conducted up to this point that can aid us in understanding the pattern that follows surgical intervention. A history of DMT2 for less than 8 years increased the likelihood of achieving the primary endpoint by four times in more extensive studies like the STAMPEDE trial (31). This study demonstrated that there is at least a window when remission is possible when DMT2 progresses in patients with hyperinsulinemia or established diabetes where MS may assist in reversing diabetes, and the earlier, the better to prevent beta cell loss. There is a rationale that suggests surgery, particularly for people with pre-operative cardiovascular disease (CVD), may be advantageous but will result in more post-operative complications than in people without a history of CVD. Nevertheless, MS provides several significant advantages in DMT2 patients with improved preoperative beta cell activity (26,39). It is clear that MS has several additional advantages, both in terms of blood glucose and insulin levels and, the scope of DMT2 remission is associated with preoperative demand for insulin (26,40).

According to a study by Dr. Ali Aminian, significant weight loss after MS, specifically SG and RYGB, and the omission of an insulin requirement was highly predictive of improvement in perceived general health (25). According to a retrospective cohort study by Mizera et al., patients in remission were significantly younger than patients who were not in remission and had diabetes for a shorter time before surgery (Table 5) (32). Diabetes-related complications were significantly less common in the surgical cohort of the study; which emphasizes that medications alone do not provide the best course of treatment for the patients suffering from diabetes.

The advanced Diabetes Remission (Ad-DiaRem) score

The Ad-DiaRem score which is calculated with the help of pre-operative clinical variables, and the likelihood of having T2DM remission within the initial 5 years following RYGB is projected to be 100%, 74.1%, 28.6%, 18.5%, and 0%, respectively, for T2DM patients with an Ad-DiaRem score of 0–5, 6–10, 11–15, 16–20, and >20. The scoring method also demonstrates that individuals with early-stage DMT2 characterized by the absence of insulin use, shorter duration of disease, and lower HbA1C seem to do better following bariatric surgery regarding remission and relapse rates (19).

Patients that may not be suited for surgery

Conditions that render a patient unfit for surgery are pregnancy, cancer (aside from non-melanoma skin cancer), ascites, peritoneal effusion, dementia, bipolar disorder, schizophrenia, cirrhosis, end-stage renal disease, human immunodeficiency virus (HIV), inflammatory bowel disease, type 1 diabetes diagnosed, diabetes secondary to a specific illness or glucocorticoid medication, prior bariatric or major abdominal surgery, or an organ transplant.

How significant can the pre-operative BMI be?

American Diabetes Association (ADA) focuses more on the baseline obesity of diabetic patients and recommends BMI >35 kg/m² for MS consideration according to 2023 management guidelines. Panunzi et al. (33,41) conducted a thorough systematic review and found that overall diabetes remission was comparable among the 60 studies with a mean preoperative BMI ≥35 kg/m² and remission rate of 71% and the 34 studies with pre-operative BMI <35 kg/m², remission was observed in 72%, respectively. Using data from 9 publications with 343 patients and follow-ups of 1–7 years, Rao et al. conducted a meta-analysis. They concluded that an average HbA1C level reduction of 2.8 points was associated with remission rates ranging from 65% to 93%. A comparable study by Müller-Stich et al. (33,42-44) found a 1.5-point decrease in HbA1C in the surgical group in their high-quality meta-analysis that included patients under age 35 (33,45). So the pertinent question is whether BMI or obesity should be the primary variable in assessing a patient’s eligibility for surgery, or if its importance has been overemphasized in the evaluation process.

BMI 25–30 kg/m²

Follow-up of 921 non-obese patients in 21 studies for 12 to 42.1 months, with the longest diabetes duration being 11.1 years, proved that 20 out of 21 studies reported remission rates ranging from 13.3% to 90.2% (36). Another RCT that included patients with a BMI of 25 to 32.2 and complete remission at 2 years found that the respective rates for the cohorts with BMIs of 25 to 27.5, 27.6 to 30, and 30.1 to 32.5 kg/m² were 35.3%, 11.1%, and 47.8% (20). One study with a sample size of 18 patients showed diabetes remission in 100% of the patients at 1 year after surgery with an HbA1C of 5.9±0.7, and the patients ranged in BMI from 27.5 to 30 kg/m² with an average duration of diabetes of 31.8 months. This study demonstrates that MS benefits patients with diabetes of all durations and insulin independence, extending beyond those already receiving intensive management (17).

Contrary to all other successful studies, one study from East Asia reported 0% remission rates in patients with BMI 27±2.5 kg/m² who underwent laparoscopic duodena-jejunal bypass (46). This result could be attributed to the study’s small sample size (n=8) or the author’s assertion that laparoscopic adjustable gastric banding (LAGB) is ineffective for improving DMT2 remission (16,21,23).

BMI 30–35 kg/m²

Cohen et al. stated that RYGB is efficient and showed 100% DMT2 remission for 6 years after surgery in the patient population of BMI 30–35 kg/m² with average DMT2 history of 13 years and the mean HbA1C 9.7, with 40% of enrolled patients were on insulin therapy (29). Indian patients were studied and showed 73% remission after 1 year but only 58% after 5 years. The study found an improvement in postoperative metabolic status. The BMI threshold for Asians is 2.5 kg/m² lower, according to ADA and the international diabetes organization (22). Diabetes patients achieved remission in 58–64% of cases in some studies on Asian subjects (16,47,48). These studies make it abundantly clear that there is room for MS to be included in the recommendations for managing diabetes.

Because glycemic improvement involves mechanisms other than weight loss, like changes in gut hormones (GLP-1 and ghrelin), bile acid signaling, intestinal nutrient sensing, and gut microbiota, these are just a few examples. The ADA should consider MS as an intervention independent of the patient’s BMI, and preoperative BMI did not significantly impact their ability to achieve diabetes remission (26).

Can the type of MS play a role in the remission of diabetes?

The various MS procedures that are currently available include RYGB, SG, OAGB, single anastomosis duodenal-ideal bypass with sleeve gastrectomy (SADI-S), biliopancreatic divesion (BPD), duodenal-jejunal bypass (DJB), and LAGB. RYGB was unequivocally superior to other types MS according to 14/31 studies, while 1/31 papers supported singleanastomosis (mini-) gastric bypass (SAGB) and 1/31 papers supported BPD as possibly the most effective surgical procedure. Our unbiased examination reveals a remission rate ranging from 11.2% to 100% based on the duration of follow-up and the patient’s preoperative health. While patients undergoing DJB had the lowest remission rates, those receiving OAGB had the highest remission rates, however with one important study finding that these groups had higher anemia levels than the RYGB group (36,49,50). Philip R. Schauer asserts that although BPD may have indicated DMT2 remission, it is also linked to more severe and frequent nutritional deficiencies (9). Anita P. Courcoulas characterized the outcomes of a randomized trial and contrasted RYGB and LAGB with lifestyle modification at 5 years. She found that the RYGB group did better at maintaining diabetes remission and required no insulin. Compared to the LAGB group, which needed insulin to achieve the same, DMT2 remission was completely absent in the lifestyle interventions group (10). According to an important publication, the four MS have the following effectiveness rating: BPD > RYGB > SG > LAGB (28). Dr. Aminian’s combined analysis of four RCTs comparing RYGB and SG for T2D improvement found no significant long-term difference between the procedures. If any difference exists, it slightly favors RYGB by 15% up to 5 years after the RCTs were done. More statistical power is unquestionably required to highlight the difference. Though diabetes is one of the many outcomes that must be considered when making decisions, the procedure selection should not be based solely on T2D-related outcomes (51).

At the 2-year follow-up, in the study conducted in Sweden, 62% of patients with DM were in full or partial remission (54.2%) or were not receiving any medical treatment. In comparison, an additional 17% had their diabetes under control and had HbA1C levels that were less than 6.5% (32). Moreover, the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) Database research highlighted potential differences in surgical outcomes between diabetic and non-diabetic patient populations, with varying results among insulin-dependent and independent patients. The outcomes like serious adverse events, readmission, reoperation, and mortality after laparoscopic sleeve gastrectomy (LSG) and laparoscopic RYGB (LRYGB) were low, ranging from 8.66% highest in the LRYGB group in insulin-dependent diabetes mellitus (IDDM) patients to as low as 0.09% in non-insulin-dependent diabetes mellitus (NIDDM) patients in LSG group. After interpreting the data mentioned by MBSAQIP, it is worth noticing that the mortality rate was the lowest (0.04%) in the non-diabetes mellitus (NDM) group in the LSG cohort, versus the highest (0.24%) in the IDDM LRYGB cohort. In comparing LSG and LRYGB, serious postoperative adverse events were higher in LRYGB across all groups: NDM (6.00% vs. 2.63% in LSG), NIDDM (6.65% vs. 3.34% in LSG), and IDDM (8.66% vs. 4.91% in LSG). Readmission rates were slightly higher for LRYGB (5.75% vs. 2.89%; 5.58% vs. 2.96%, 7.02% vs. 4.99%), for NDM, NIDDM, and IDDM respectively). Mortality rates were generally low but slightly higher in LRYGB patients, especially in the IDDM group (0.24% vs. 0.15%); reoperation rates were also higher for LRYGB in all groups: NDM (2.24% vs. 0.78%), NIDDM (2.15% vs. 0.92%), and IDDM (2.16% vs. 1.22%). Interestingly enough, it is important to underline that in each cohort highest rate of mortality and complications were noticed in the IDDM group, however the rate of mortality. reoperation, readmission, and adverse effects are lower in the LSG IDDM group versus LRYGB-NIDDM and IDDM group (except the mortality rate of 0.15% in LSG IDDM vs. 0.14% in the NIDDM LRYGB group) (26). Given that SADI-S is still in its infancy, no level 1 long-term evidence studies show enhanced metabolic outcomes with manageable dietary risks compared to RYGB or SG (29). When OAGB patients were followed up, some patients lost 100% of their excess weight, according to Ruiz-Tovar et al. (52). During the 2-year follow-up, 16% of OAGB patients had bile in their stomachs, an etiology for gastric cancer that should be taken seriously. RYGB and BPD were compared with pharmacotherapy by Philip R. Schauer, who also established that BPD may be superior to RYGB over a 5-year follow-up study (Figure 2) (15).

Figure 2 Area graph of the number of patients that showed diabetes remission at 2 and 5 years postoperatively. Patients undergoing pharmacotherapy (n=20) showed no remission as compared to patients on RYGB (n=20) and BPD (n=20). RYGB, Roux-en-Y gastric bypass; BPD, biliopancreatic diversion.

Post-operative complications

Early complications reported most frequently were gastrointestinal bleeding, leakage, fistulas, and the need for subsequent surgical intervention. There was evidence of leakage, or “fistula”, in 4 studies with incidence rates of 1% to 4%. In addition, incidence rates of protracted nausea or vomiting ranged from 3% to 56%, according to Geloneze et al. (28,53).

The long-term effects frequently mentioned were anemia, stomach stasis, gastroplegia, marginal ulcers, and esophagitis. Four trials utilizing RYGB or OAGB also found a significant incidence of anemia, with rates of 8%, 9%, 20%, and 33%. In three studies, the prevalence of marginal ulcers was reported as 7%, 15%, and 17%. It is important to note that only people receiving GB were found to have anemia, osteopenia, reflux esophagitis, and marginal ulcers. Consistent nausea or vomiting (56%), anemia (33%), and stomach stasis or gastroplegia (27%) ranked as the top 3 problems by frequency of recurrence. Wound infection at 1%, abdominal pain at 1.8%, leakage at 0.7%, nutritional insufficiency at 0.4%, abscess/deep infection at 0.4%, and pulmonary complications at 0.4% were also noted, each with its rates (36) (Figure 3).

Figure 3 Occurrence rate of post-operative complications throughout the analysis.

Oxalate nephropathy may develop following MS, resulting in chronic renal disease and nephrolithiasis. Although it is challenging to quantify, this risk appears method-dependent (18). A potential risk factor for post-operative retinal worsening is the degree of pre-operative disease. The likeliness of higher degrees post-operatively tends to increase regardless of how early retinopathy develops. Most people with no retinopathy before surgery remain disease-free (18,54-57). The remaining surgical procedures mainly have physiological consequences such as dumping syndrome, prolonged nutritional deficits, reduced bone density, and formation of kidney/gallbladder stones.

Noticeable benefits in the surgical patients

In comparative RCTs, surgical groups had four times fewer hypertension and five times fewer dyslipidemia risks (8,45). Lower cholesterol, triglycerides, blood pressure (systolic and diastolic), and low-density lipoprotein reduced comorbidities, complications, and 10-year heart attack and stroke risk (8). MS is more effective than medication alone in treating hypertension.

Since MS can successfully treat hypertension and dyslipidemia, it may also be more effective than pharmacotherapy in treating already-present diabetic kidney disease (18,58,59). O’Brien’s 5-year study of 4,024 T2DM patients found a 59% decrease in the risk of nephropathy after MS (37,45,60). The results showed that the risk of cumulative incidence of nephropathy was reduced by 59% (52). In a prospective case-control study involving 70 patients with T2DM who underwent gastric bypass (GBP), the albumin creatine ratio (ACR) significantly decreased over the first postoperative year (37,59). In a study by Liakopoulos et al. (37) involving 5,321 surgical patients and 5,321 control subjects with a mean follow-up of 4.5 years and a BMI of >40 kg/m², the renal and cardiovascular outcomes (Figure 4) after GBP were assessed. Thus, it is important to note that the healthcare cost associated with comorbidities will be reduced. Le Roux et al. found no increased mortality in DMT2 patients after MS, but those who achieved remission had lower mortality rates (11).

Figure 4 Graphical representation of renal and cardiovascular outcomes in gastric bypass and control group (pharmacotherapy), the numbers as studied by Liakopoulos et al. (37). eGFR CKD-EPI, estimated glomerular filtration rate using the Chronic Kidney Disease Epidemiology Collaboration equation; CVD, cardiovascular disease; CHF, chronic heart failure; GBP, gastric bypass.

Relapse of diabetes

The Swedish Obese Subjects’ study reports that early change in weight is a sign of T2D relapse after MS (61). A study found that 54% of patients were in remission at the 2 years mark; however relapse rates were notably high at 10 and 15 years. Patients who experienced relapse had higher BMIs and blood glucose levels before surgery. Models predicting relapse were ineffective, but weight loss after 2 years was linked to relapse, emphasizing the importance of early intervention. Immediate treatment after relapse could benefit patients. Remission and relapse groups had comparable baseline ages and insulin levels. Still, weight reduction after 2 years was linked to relapse, highlighting the importance of early weight loss in controlling T2D long-term (20).

Conclusive potential standard management of diabetes

To achieve long-lasting remission of diabetes, a treatment including MS, nutrition supplements, and medication like sodium-glucose cotransporter-2 (SGLT2) inhibitors following surgery has a high chance of success after the analysis of 31 studies. MS should not be a last resort, as advanced-stage diabetes with permanent beta cell damage may make it ineffective (13). Follow-up should be frequent for the first 2 years and then annually, with regular glycemic control checks (27).

Recommendations and future scope of research

The various definitions of DMT2 remission brings a minor disparity in published remission and relapse rates, hence a universally defined criteria needs to be formed. Strict BMI thresholds for prioritizing MS have been repeatedly shown to be ineffective because non-eligible (per DiaRem) patients may benefit from equivalent as eligible patients. The prolonged effects of surgery are unknown because most of the meta-analysis studies only had a brief follow-up period, some with small sample sizes. The need for extensive, large-scale cohort studies exists, examining how surgery affects retinopathy and nerve function in patients with and without active diabetic foot disease, given the risk of injury (ulceration or arthropathy) and lean mass loss. It is crucial to distinguish between respondents, patients who did not exhibit remission, and those who relapsed. Extensive RCTs comparing MS with non-surgical options such as SGLT2 inhibitors and glucagon-like peptide one receptor agonists, the latter of which seem to have significant positive effects on the cardiovascular system and mortality, are needed. Observational studies suggest that MS reduces the risk of cancer and can improve sleep apnea, osteoarthritis, and incontinence results than non-surgical treatment. However, randomized controlled trials are required to verify these observations. There needs to be more research done to confirm the role of ethnicity (18,62). The impact of surgical intervention models on international healthcare practice policy and economics needs to be studied. Pre-clinical studies specifically focussing on the interplay of hormones like glucagon-like peptide 1, gastric inhibitory peptide, ghrelin, fibroblast growth factor-19, insulin, glucagon, adiponectin, leptin, and markers like tumor necrosis factor-α, interleukin-6 play, and bile acids; and analyze their role a role in this remission and relapse of diabetes after the anatomical rearrangement, can be a promising research area.

Limitations

This review could not address the resolution of co-morbidities and the occurrence of complications due to insufficient information disclosure or inconsistent interpretations of co-morbidities and complications across studies. Physicians (mostly endocrinologists and cardiologists) and surgeons continue to make recommendations that differ significantly from one another (32). Whether the physician has read the clinical or surgical guidelines will affect the course of treatment for the same patient, and also the guidelines will vary from one country to another. This review was limited to studies published in English language only.

Conclusions

Defining diabetes mellitus remission uniformly rather than just saying “controlling hyperglycemia” will be the first and most important step. We must be aware that glycemic outcomes can be significantly impacted by non-surgical weight loss, that is oral medications, insulin and life-style changes and it should be the first approach in management and should be continued with patients for whom surgery is not feasible, essential, or desirable; however the studies have given strong evidence that an aggressive pharmacological and lifestyle change treatment does not stand anywhere close to the remission rates after undergoing MS and MS has consistently demonstrated superior results in the remission of diabetes. It is worth noting that the results of diabetes control may vary widely between different procedures, and complementary medicine should be tailored to each patient’s specific condition. MS has become a potential adjunctive treatment for DMT2 patients. After this high-quality study, it should be safe to say that the best remission probability lies in the patient subgroup who has less than 10 years of DMT2 history and who are non-insulin dependent diabetes mellitus subgroup of patients; but this does not imply remission is limited to non-insulin dependent patients. The currently available management protocol by ADA might have over emphasized on the BMI as an eligibility criteria while incorporating MS in the treatment; it should be noticed that results of remission rates in lower BMI (25 to 35 kg/m²) have been impressive clinically, and life changing from a patient’s perspective, that being said the pre-operative BMI might be more useful to predict the relapse rate after going through remission. While Roux-en-y has been proven to be most effective procedure so far; it is probably because it has been the most popular choice among surgeons widely across globe. Newer procedures like OAGB and SADI-S must be incorporated for innovation in surgical models and is crucial to the development of metabolic surgical capacity building, clinical training and infrastructure globally. MS has the potential to reduce long-term healthcare costs burden with expensive medications and DMT2 associated complications; while offering an effective way to manage diabetes. We do not believe that the importance of MS for DMT2 can be overstated. By integrating MS into an accounting equation, we can work to ensure that this life-changing procedure is accessible to everyone who needs it, regardless of socioeconomic situation. For healthcare professionals, decision-makers, and researchers to address the disease’s growing impact globally, there is an urgent need to focus on diabetes’s rising prevalence and its associated complications.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the PRISMA reporting checklist. Available at https://aos.amegroups.com/article/view/10.21037/aos-23-4/rc

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://aos.amegroups.com/article/view/10.21037/aos-23-4/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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