Gastric bypass, sleeve gastrectomy ‘substantially’ reduce liver fat in type 2 diabetes
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Roux-en-Y gastric bypass and sleeve gastrectomy are equally effective at reducing hepatic steatosis, with an almost complete clearance of liver fat 1 year after the surgical procedures, according to data from a single-center study.
“With an almost complete clearance of liver fat 1 year after surgery, our study provides new high-quality evidence that the two most common weight loss surgeries, Roux-en-Y gastric bypass and sleeve gastrectomy, appear to be highly effective in reducing liver fat content in patients with type 2 diabetes and obesity,” Jens Kristoffer Hertel, PhD, head of research at the Morbid Obesity Centre at Vestfold Hospital Trust in Tønsberg, Norway, told Healio. “However, the effect of these weight loss surgery approaches on liver scarring is more unclear.”
In a randomized controlled trial, Hertel and colleagues analyzed data from 100 patients with type 2 diabetes from a tertiary care obesity center in Norway (65% women; mean age, 48 years; mean BMI, 42 kg/m2). From January 2013 to February 2018, researchers randomly assigned patients to sleeve gastrectomy or Roux-en-Y gastric bypass. The study’s primary outcome of remission of type 2 diabetes was previously published; predefined secondary outcomes for the new analysis were hepatic steatosis and fibrosis assessed by MRI (liver fat fraction), enhanced liver fibrosis (ELF) test, noninvasive indices and liver enzymes.
The findings were published in Annals of Internal Medicine.
From surgery to 1-year follow-up, researchers found liver fat fraction declined similarly after sleeve gastrectomy (mean, –19.7%; 95% CI, –22.5 to –16.9) and Roux-en-Y gastric bypass (mean, –21.5%; 95% CI, –24.3 to –18.6). Almost all patients — 94% who underwent sleeve gastrectomy and 100% who underwent gastric bypass — had no or low-grade steatosis at 1 year.
The ELF score category remained stable for 77% of patients; however, 18% experienced worsening of fibrosis at 1 year, with no between-group difference.
“Both Roux-en-Y gastric bypass and sleeve gastrectomy appear to be effective in reducing liver fat content,” Hertel told Healio. “Our study also shows that the liver fat content was reduced dramatically during the first 5 weeks after surgery, indicating that the first 10% of weight loss achieved is the most important regarding fatty liver disease. Together, this might have clinical implications for the treatment of fatty liver disease.”
The researchers noted the study recruited mostly white patients and had short follow-up; however, the study is ongoing, with follow-up planned to 5 years.
“Both procedures stand out as appropriate treatment options to reduce the burden of nonalcoholic fatty liver disease,” the researchers wrote. “The ELF test results might suggest a slight worsening in liver fibrosis after bariatric surgery, but further research is warranted on long-term progression or regression of fibrosis.”
For more information:
Jens Kristoffer Hertel, PhD, can be reached at jehert@siv.no.
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Christos S. Mantzoros, MD, DSc, PhD
The authors report that both Roux-en-Y gastric bypass and sleeve gastrectomy reduce hepatic steatosis at 1 year. This is confirmatory of what is generally expected on the basis of induced weight loss.
The study did not assess inflammation, and the tools for assessing fibrosis are widely available but rather suboptimal. In this respect, the findings on fibrosis need to be considered as hypothesis generating only and highlight the need for further research.
Indeed, a recently published retrospective electronic health record review from the Cleveland Clinic that assessed patients after bariatric surgery vs. controls for up to 10 years suggested a major improvement in CV and liver outcomes. Our own preliminary unpublished data of bariatric surgery patients who underwent either Roux-en-Y gastric bypass or sleeve gastrectomy and who were followed for at least 10 years after surgery indicate that fibrosis indexes are improved over time.
Long-term studies with appropriate study design, selection criteria for participants and methods for evaluation of fibrosis are needed to fully elucidate clinical results and mechanisms leading to improvements in liver inflammation and fibrosis status after bariatric surgery.
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Johanna DiStefano, PhD
It is widely recognized that bariatric surgery can remit type 2 diabetes in some patients, but the effects of weight-loss surgery on NAFLD remission are not as well understood. Seeberg and colleagues performed a single-center, randomized controlled trial to explore the effects of sleeve gastrectomy and Roux-en-Y gastric bypass on hepatic steatosis and fibrosis at 1 year after surgery. The study enrolled 100 participants with type 2 diabetes and obesity and randomly assigned these individuals to sleeve gastrectomy and Roux-en-Y gastric bypass. At 1 year, liver fat fraction was measured using MRI and chemical shift imaging, while fibrosis was quantified using the ELF test. Both sleeve gastrectomy and Roux-en-Y gastric bypass led to significant reductions in liver fat fraction at 5 weeks and 1-year postsurgical intervention, with most patients in both groups showing either no or low-grade steatosis. Despite the significant improvements in hepatic steatosis and levels of liver enzymes in both groups, the effects of surgery on liver fibrosis were less clear. Nearly 20% of patients exhibited worsening of fibrosis, compared with only 5% who showed improvement.
Although this study was limited by the unavailability of histological diagnosis, a relatively short time to follow-up and a sample size that was underpowered for the analyses, the findings are important because they represent one of the first randomized controlled trials comparing the effects of sleeve gastrectomy and Roux-en-Y gastric bypass on liver fat reduction and fibrosis. This work also adds to the growing body of literature indicating a significant impact of weight-loss surgery on NAFLD remission in individuals with obesity and warrants the need for further studies to assess bariatric surgery-mediated effects on long-term progression of the disease.
Given the escalating global prevalence of NAFLD, the lack of approved pharmacological treatments, and the difficulty of implementing and sustaining diet and physical activity modifications, which is the front-line approach to managing NAFLD, more effective efforts to mitigate NAFLD are urgently needed.
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Metabolic-associated fatty liver disease is highly prevalent in the bariatric population, and steatohepatitis/fibrosis is a more advanced form of nonalcoholic fatty liver disease (NAFLD) that is more common among those with diabetes. Weight loss of 10% or greater is indicated for such patients but results from lifestyle modification are difficult to sustain in the long term. Bariatric surgery results in greater weight loss that is more durable than lifestyle modification and some anti-obesity pharmacotherapies.
Hertel and colleagues examined liver fat among adults with type 2 diabetes after gastric bypass and sleeve gastrectomy and found that both procedures markedly reduced liver fat at 1 year. These data are important for clinical care of patients with type 2 diabetes and obesity, especially in those with BMI greater than 35 kg/m2 who meet the criteria for bariatric surgery. For those under this BMI, it is still important to screen for NAFLD with noninvasive liver scores (FIB-4) and imaging (Fibroscan [Echosens], magnetic resonance elastography) and initiate weight management. Referral to hepatology is indicated for patients with advanced NAFLD/nonalcoholic steatohepatitis (NASH) for management of cirrhosis.
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Seeberg KA, et al. Ann Intern Med. 2021;doi:10.7326/M21-1962.
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