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Weight loss surgery linked to lower CV event risk in diabetes

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A ‘preferred treatment option’ in obesity and type 2 diabetes?

Despite a focus on reducing macrovascular events in individuals with type 2 diabetes, none of the major randomized controlled trials of glucose-lowering interventions that support current treatment guidelines have achieved this outcome. This study of bariatric surgery in obese patients with diabetes, however, does show reductions in major adverse cardiovascular events, although these outcomes should be interpreted with caution because of their observational nature and imprecise matching of the study groups.

Despite this, the many known benefits associated with bariatric surgery–induced weight loss suggest that for carefully selected, motivated patients with obesity and type 2 diabetes – who have been unable to lose weight by other means – this could be the preferred treatment option.

Dr. Edward H. Livingston is the deputy editor of JAMA and with the department of surgery at the University of California, Los Angeles. These comments are adapted from an accompanying editorial (JAMA 2019, Sept 2. DOI:10.1001/jama.2019.14577). No conflicts of interest were declared.



Weight-loss surgery in people with type 2 diabetes and obesity is associated with significant reductions in major adverse cardiovascular events, compared with nonsurgical management, according to data presented at the annual congress of the European Society of Cardiology.

The retrospective cohort study, simultaneously published in JAMA, looked at outcomes in 13,722 individuals with type 2 diabetes and obesity, 2,287 of whom underwent metabolic surgery and the rest of the matched cohort receiving usual care.

At 8 years of follow-up, the cumulative incidence of the primary endpoint – a composite of first occurrence of all-cause mortality, coronary artery events, cerebrovascular events, heart failure, nephropathy, and atrial fibrillation – was 30.8% in the weight loss–surgery group and 47.7% in the nonsurgical-control group, representing a 39% lower risk with weight loss surgery (P less than .001).

The analysis failed to find any interaction with sex, age, body mass index (BMI), HbA1c level, estimated glomerular filtration rate, or use of insulin, sulfonylureas, or lipid-lowering medications.

Metabolic surgery was also associated with a significantly lower cumulative incidence of myocardial infarction, ischemic stroke and mortality than usual care (17% vs. 27.6%).

In particular, researchers saw a significant 41% reduction in the risk of death at eight years in the surgical group compared to usual care (10% vs. 17.8%), a 62% reduction in the risk of heart failure, a 31% reduction in the risk of coronary artery disease, and a 60% reduction in nephropathy risk. Metabolic surgery was also associated with a 33% reduction in cerebrovascular disease risk, and a 22% lower risk of atrial fibrillation.

In the group that underwent metabolic surgery, mean bodyweight at 8 years was reduced by 29.1 kg, compared with 8.7 kg in the control group. At baseline, 75% of the metabolic surgery group had a BMI of 40 kg/m2 or above, 20% had a BMI between 35-39.9, and 5% had a BMI between 30-34.9.

The surgery was also associated with significantly greater reductions in HbA1c, and in the use of noninsulin diabetes medications, insulin, antihypertensive medications, lipid-lowering therapies, and aspirin.

The most common surgical weight loss procedure was Roux-en-Y gastric bypass (63%), followed by sleeve gastrectomy (32%), and adjustable gastric banding (5%). Five patients underwent duodenal switch.

In the 90 days after surgery, 3% of patients experienced bleeding that required transfusion, 2.5% experienced pulmonary adverse events, 1% experienced venous thromboembolism, 0.7% experienced cardiac events, and 0.2% experienced renal failure that required dialysis. There were also 15 deaths (0.7%) in the surgical group, and 4.8% of patients required abdominal surgical intervention.

“We speculate that the lower rate of [major adverse cardiovascular events] after metabolic surgery observed in this study may be related to substantial and sustained weight loss with subsequent improvement in metabolic, structural, hemodynamic, and neurohormonal abnormalities,” wrote Ali Aminian, MD, of the Bariatric and Metabolic Institute at the Cleveland Clinic, and coauthors.

“Although large and sustained surgically induced weight loss has profound physiologic effects, a growing body of evidence indicates that some of the beneficial metabolic and neurohormonal changes that occur after metabolic surgical procedures are related to anatomical changes in the gastrointestinal tract that are partially independent of weight loss,” they wrote.

The authors, however, were also keen to point out that their study was observational, and should therefore be considered “hypothesis generating.” While the two study groups were matched on 37 baseline covariates, those in the surgical group did have a higher body weight, higher BMI, higher rates of dyslipidemia, and higher rates of hypertension.

“The findings from this observational study must be confirmed in randomized clinical trials,” they noted.

The study was partly funded by Medtronic, and one author was supported by the National Institute of Diabetes and Digestive and Kidney Diseases. Five authors declared funding and support from private industry, including from Medtronic, and one author declared institutional grants.

SOURCE: Aminian A et al. JAMA 2019, Sept 2. DOI: 10.1001/jama.2019.14231.

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