Answer

Literature Review

The purpose of this study is to examine the effect of bariatric surgery to obese adult patients who undergone bariatric surgery and to compare the effectiveness of bariatric surgery with non-surgical management.  Numerous studies have been conducted to explore the effectiveness of bariatric surgery in adults with Type 2 DM. In the literature review the researcher focused on obese adults with Type 2 DM.

In the Surgical Treatment and Medications Potentially Eradicate Diabetes Efficiently (STAMPEDE) trial study done by Schauer and associates (2017), it was concluded that within one year and three years after randomization, bariatric surgery (gastric bypass and sleeve gastrectomy) were SUPERIOR than intensive medical therapy in ACHIEVING EXCELLENT glycemic control (HbA1C less than 6), reducing cardiovascular risks, improving quality of life and decreasing medication use. A 5-year follow – up study was instituted to explore the long-term effects and SAFETY of bariatric surgery in Type 2 DM. It was noted during that period that patients who had undergone bariatric surgery (gastric bypass or sleeve gastrectomy) had significant likelihood of achieving and maintaining a glycated hemoglobin level of 6% or less with or without medication, than those who received intensive medical therapy alone. Also analyzed in the study were secondary end points like BMI, body weight, levels of triglycerides and cholesterol and quality of life. The results at 5 years were more favorable in the surgical group than the medical therapy group. A majority of the surgical patients who achieved a glycated hemoglobin level of 6% or less reached that target with or without the use of diabetes medications, whereas none of the patients in the medical group reached the target without the use of diabetes medications. Additionally, significant and durable decreases in bodily pain and improvements in general health in the surgical groups were observed as compared to the medical therapy group at five years. The quality of life was also superior among patients who had undergone bariatric surgery as compared to those who received intensive medical therapy.

Strong Evidence now demonstrates that bariatric procedures markedly improve or cause remission of Type 2 DM as noted in a study by Cummings and associates (2016) of a meta-analysis of the 11 published Randomized Clinical Trial (RCT) comparing bariatric surgery to medical/lifestyle intervention. In a systematic review and pooled meta-analysis of only level 1 and 2 evidence which included seven Randomized Clinical Trials and six high-quality prospective observational comparisons,

Muller-Stich and associates (2015) found that various surgical interventions were statistically more superior to non-surgical interventions in causing diabetes remission and glycemic control, in the study, the overall odds ratio (OR) for surgical superiority in diabetes remission was 14.1 among all studies and 22 among those that exclusively examined patients with a preoperative BMI <35 kg/m^2. They also found that the BMI of these patients fell much more with surgery than with medical/lifestyle interventions and these patients were four times less likely to have hypertension and five times less likely to have dysplipidemia compared to the medical group.

It is noted that all 11 RCTs reported superior results from surgery compared to medical/lifestyle interventions for diabetes remission and/or glycemic control. Less than 35kg/m BMI is included in the sample as NIH is only recommending bariatric surgery for BMI greater than 40.  It is mentioned in this article that these operations should be viewed not just bariatric surgery but also metabolic surgery. The fact that bariatric surgery has superior efficacy in treating Type 2 DM means it should be considered as an alternative treatment for Type 2 DM in less obese patients with BMI of less than 35 and that NIH should change the guideline limiting the surgery to severely obese patients with BMI of more than 40.

A smaller systematic review and meta-analysis recently published by Rao et al (2015) examined the effects of RYGB on Type 2 DM among studies whose participants exclusively had a baseline BMI <35 kg/m². This study comprised nine publications which described a total of 343 participants with baseline BMI between 19–35 kg/m² and were followed-up from first to seventh year. They reported no deaths and surgical complication rates were 6–20%, which is similar to rates published for patients with a baseline BMI ≥35 kg/m² as described by Rubino and associates (2015). All nine articles studied in this review reported significant HbA1C reductions after surgery, with an average percent HbA1C lowering of 2.8 points. Overall, bariatric surgery led to a reduction in fasting blood glucose by 60 mg/dL which was more than did the various nonsurgical comparator interventions. The rates of diabetes remission which was defined here as HbA1C less than 6.5% off all diabetes medications ranged from 65% to 93%, which is at least as high as is reported historically among patients with a baseline BMI ≥35 kg/m²

Obesity and Diabetes have reached epidemic Proportions and comprise a major health problem worldwide. The Incidence of diabetes can be reduced by as much as 50% by lifestyle and pharmacological interventions. Bariatric surgery reduced the long-term incidence of diabetes by about 80% in the findings in the Swedish Obese Subjects (SOS) observational long term follow-up study of 2, 10, 15 years. In a Swedish study by Sjostrom and associates (2014) with 260 of 2037 control group and 343 of 2010 surgery patients from 25 surgical departments and 480 primary health care centers in Sweden.  Inclusion and exclusion criteria were the same for both sample groups. It is also reported in this study that microvascular and macrovascular events were reduced with bariatric surgery. In this very long term follow-up observational study, it is noted that obese patients with Type 2 DM who underwent bariatric surgery had more frequent diabetes remission and fewer complications than standard care.

A randomized controlled trial by Mingrone and associates (2015) included patients aged 30-60 years with a BMI of 35kg.m2 or more and a history of Type 2 DM lasting at least five years. The primary endpoint of the study was the rate of diabetes remission at 2 years which was defined as HbA1C < 6.5% and a fasting blood glucose of 5 -6 mmol/l or less without active pharmacological treatment for one year. they conducted a follow-up for five years. They found that 42% of patients who had gastric bypass surgery and 28% of those who underwent biliopancreatic diversion surgery had HbA1C of 6.5% or less with or without medication compared to 27%  medically treated patients. The surgical group also lost more weight than medically treated group though this did not predict diabetes remission or relapse after surgery. Those with surgical procedures had significantly lower plasma levels of lipids and also had lower cardiovascular risks. Five major complications of diabetes which included one fatal myocardial infarction was observed in 27% of patients in the medical group compared with only one complication in the gastric bypass group and no complications in the biliopancreatic diversion group. No late complications or deaths occurred in the surgery groups.

In a study by Simona and associates (2016) based on 727 sample, 415 underwent bariatric surgery.  Patients with BMI of less than 35 and BMI of more than 35 were included. This is considered a large analysis to focus on the best predictors of diabetes remission after bariatric surgery in Caucasian population. As a result, bariatric surgery resulted in euglycemia in a significant number of subjects.  Diabetes remission occurred in 63.7% of the patients in the surgical arm and 14.4% of those in the medical arm. It is noted that GD procedures were more effective than GO procedures in terms of diabetes remission.  It is emphasized in the study that duration of diabetes of less than or equal to 1.5 years fasting glycemia of less than 7.6 and absence of insulin therapy predicted a better outcome, these parameters did not influence the effect of RYGB and BPD on diabetes remission. Overall, the best predictors of improvement of glycemic control after bariatric surgery were smaller waist circumference, better controlled diabetes and lower triglyceride levels at baseline. In addition, responders lost more weight and waist circumference after bariatric surgery, had a greater reduction in plasma triglycerides, and became more insulin resistance. It is noted that predictors of diabetes remission differs in relation to the type of bariatric surgery, whereas better glycemic control with smaller waist circumference at baseline. Another finding was BMI was not dependent on diabetic remission after bariatric surgery, therefore suggesting that bariatric surgery could be a therapeutic option for patients with Type 2 DM and abdominal obesity even with BMI between 30 and 35 kg/m.

Dixon and associates (2013) conducted a study on 154 Chinese patients in Taiwan. The aim of the study was to determine the level of HbA1C at 12 months after surgery. Another purpose of the study was to explore the preoperative factors that would determine the outcome of bariatric-metabolic surgery. The study identified 3 factors which were longer duration of diabetes disease, lower C-peptide level and lower BMI. It is noted that these factors decreased the likelihood of response to surgery. The study identified not only preoperative factors to achieve remission but also those useful in identifying the likelihood of having HbA1C less than or equal to 7% after surgery. The study noted that diabetic remission was experienced in 107 subjects at 12 months after surgery. It is further noted that diabetes duration of less than 4 years, body mass of more than 35 kg, and fasting C-peptide of more than 2.9 were considered as preoperative factors in achieving diabetic remission after bariatric surgery. ..

            Koliaki, Liatis, le Roux and Kokkinos (2017) examined the role of bariatric surgery in the treatment of Type 2.DM. The aim of their study was to discuss the major pathophysiological mechanisms mediating weight loss and Type 2 DM remission after bariatric surgery, summarize the clinical and biological predictors of T2DM remission after surgery, and provide an update on the short, mid- and long-term effects of bariatric surgery in obese patients with Type 2 DM with a focus on weight loss durability, Type 2 DM remission, improvement of cardiovascular risk factors, diabetes-related complications, mortality and survival. They found that metabolic surgery was able to reduce and maintain a substantial weight loss through calorie restriction and altered eating behavior patterns. An Australian open-label study in 60 patients with BMI 30–40 kg/m² with recently diagnosed Type 2 DM was also examined in this study which compared LAGB to conventional diabetes therapy with focus on weight loss and Type 2 DM remission for a follow-up period of 2 years, and reported Type 2 DM remission rates of 73% in the surgical group versus only 13% in the control group. They found that weight loss after LAGB was nearly 10-fold higher (20.7% vs. 1.7%). In this study, Type 2 DM remission was related to the extent of weight loss and lower baseline HbA1C levels. In another Randomized Controlled Trial in 50 overweight patients with Type 2 DM randomly allocated to intensive diabetes care with or without LAGB, Type 2 DM remission at 2 years was achieved in 50% of LAGB patients, and 8% in the control group (Wentworth et al., 2014). In contrast with the above data, another RCT in obese patients with Type 2 DM comparing LAGB with an intensive medical weight management program, reported similar HbA1C reductions at three and twelve months in both groups, similar weight loss at 3 months and similar changes in blood pressure, serum lipids, cardiovascular risk scores and patient-reported health outcomes after both interventions, thus questioning the real potential of LAGB to powerfully affect cardiometabolic outcomes in this population (Ding et al., 2015).

            In a systematic review and meta-analysis study by Baskota, Li, Dhakal, Liu and Tian (2015), they investigated the metabolic changes after surgical treatment in diabetic patients with BMI less than 30 kg/m2. They conducted ten prospective studies which involved a total of 290 type 2 DM patients with a mean age of 51 years and a follow up interval of between three months to two years. All the participants had  mean duration of diabetes of 2 to 20 years and underwent bariatric surgery for the purpose of glycemic control. All the ten studies reported mean changes in the BMI. Compared with the preoperative status, the BMI reduction was 2.79 kg/m² after surgery while the overall body weight loss was 9.71 kg. Statistically significant improvements in the glycated hemoglobin and Fasting Blood Glucose levels after surgery were observed in the pooled analysis of the ten articles. Compared with the studies in patients with higher BMI levels, the trend was consistent; however, the level of improvement was lower. These results suggested that various metabolic surgeries could lead to significant reduction in insulin administration, as well as the use of oral medication, regardless of the surgical procedure.

            Aung and associates (2016) compared the short-term and long-term outcomes of bariatric surgery specifically focusing on the rate of remission of Type 2 DM in patients with early onset and late onset Type 2 DM. They conducted a cohort study involving 558 Taiwanese patients of which 339 had early onset disease and the remainder had late onset disease with a BMI above 25. Those with early-onset Type 2 DM had higher mean preoperative BMI and HbA1C values (39.4  and 8.7% ) respectively than did patients with late-onset Type 2 DM (36.7 and 8.2%) respectively. Distribution of surgical procedures and major complications were similar between the two groups. They reported a higher rate of complete remission of Type 2 DM in patients with early-onset disease than in those with late-onset disease (193 [56.9%] vs 110 [50.2%]). At 5 years, the patients with early-onset disease still had maintained a higher rate of weight loss (30.4% vs 21.6% ) and higher rate of remission (65.3% vs 54.2%) than did those with late-onset disease. The age at bariatric surgery, duration of disease, and preoperative C-peptide level were also found to be independent predictors of remission which further was directly related to extent of weight loss. Their study concluded that bariatric surgery may achieve better and more long-lasting glycemic control in select patients with early-onset Type 2 DM than in those with late-onset Type 2DM.