Metabolic surgery may improve cardiovascular prognosis in type 2 diabetes
medwireNews: People with type 2 diabetes and obesity who undergo metabolic surgery have a significantly lower risk for major adverse cardiovascular events (MACE) than those who do not receive surgery, observational study data show.
However, Steven Nissen (Cleveland Clinic, Ohio, USA) and co-investigators caution that the observational nature of the study means their findings “should be considered hypothesis-generating and not conclusive” and “must be confirmed in randomized clinical trials.”
The retrospective analysis included data for 2287 individuals with type 2 diabetes (mean glycated hemoglobin [HbA1c] 7.1%) and obesity (mean BMI 45.1 kg/m2) who underwent metabolic surgery and 11,435 controls matched for sex, age, BMI, and HbA1c who received usual care. Metabolic surgery included Roux-en-Y gastric bypass (63.1%), sleeve gastrectomy (31.9%), adjustable gastric banding (4.8%), and duodenal switch (0.2%).
During a median follow-up period of 3.9 years, 385 patients in the surgical group and 3243 patients in the nonsurgical group experienced MACE, defined as coronary artery events, cerebrovascular events, heart failure, nephropathy, atrial fibrillation, and all-cause mortality. This corresponded to 8-year cumulative incidence rates of 30.8% and 47.7%, respectively.
After adjustment for potential confounders, the researchers found that surgery was associated with a significant 39% lower risk for MACE, relative to no surgery.
Furthermore, the risk for each of the individual MACE components, as well as a composite of myocardial infarction, ischemic stroke, and mortality were all significantly lower with versus without surgery, with risk reductions ranging from 22% for atrial fibrillation to 62% for heart failure.
The 8-year cumulative mortality rates were 10.0% and 17.8% among the patients who did and did not receive surgery, respectively, with patients in the surgical group having a significant 41% lower risk for death than those in the nonsurgical group.
Nissen and team also note that metabolic surgery was associated with a significant 1.1% greater reduction in HbA1c from baseline and a significant 20.3 kg greater weight loss relative to no surgery.
Writing in JAMA, the investigators suggest “that the lower rate of MACE 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.”
In an accompanying commentary, Edward Livingston, from the University of California in Los Angeles, USA, asks what the best treatment option is in 2019 for obese people with type 2 diabetes.
He writes “The results from drug studies, although of relatively high quality, suggest limited effect on long-term macrovascular outcomes. In contrast, bariatric surgery appears to improve long-term outcomes, including mortality, but the quality of evidence is not as high.”
Livingston concludes: “When balancing the imperfections in the evidence for both medical and surgical treatment of diabetes, the many benefits associated with bariatric surgery–induced weight loss suggest that it should be the preferred treatment option for carefully selected, motivated patients who are obese and have diabetes and cannot lose weight by other means.”
By Laura Cowen
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