medwireNews: Weight loss after gastric bypass surgery results in important cardiovascular (CV) and renal benefits for obese people with type 2 diabetes, irrespective of their baseline renal function, observational cohort study data show.
“While the effects of bariatric surgery on renal function in obesity and [type 2 diabetes] remain to be confirmed in prospective trials, our findings add strong support for intentional weight loss as a legitimate intervention to prevent or delay renal dysfunction and related cardiac outcomes,” Vasileios Liakopoulos (University of Gothenburg, Sweden) and colleagues remark.
Liakopoulos and team used registry data to identify 5321 individuals with type 2 diabetes and obesity who underwent gastric bypass between 2005 and 2017, matching them by estimated propensity score to 5321 who did not undergo surgery, based on a model including age, sex, BMI, and time.
By 2 years postsurgery, BMI, glycated hemoglobin, and creatinine levels were all significantly lower among the people who had undergone surgery relative to those who had not, while estimated glomerular filtration rate (eGFR) was significantly higher.
In addition, the number of individuals who developed macroalbuminuria was 305 in the gastric bypass group compared with 575 in the control group, which corresponds to a 45% total risk reduction.
At a mean follow-up of 4.6–4.7 years, the incidences of all but two of the 17 outcomes relating to renal function, CV disease, and mortality were significantly lower among the people who had received gastric bypass than among those who did not. After adjustment for sex, age, BMI, eGFR, marital status, income, education, and country of birth, hazard ratios (HRs) ranged from 0.22 to 0.82 and were most marked for diabetic nephropathy (HR=0.22), heart failure (HR=0.33), and CV mortality (HR=0.36).
Furthermore, the risk for all-cause mortality was a significant 42% lower among the patients who underwent surgery, while the risk for a composite of severe renal disease or halved eGFR was 44% lower.
The researchers also compared the incidence of each of the outcomes according to eGFR and observed a clear risk reduction across all eGFR strata for the majority of outcomes. For example, the risk for the composite renal outcome was a nonsignificant 43% lower with versus without surgery among people with an eGFR of 45–60 mL/min per 1.73 m2, and was a significant 63% and 60% lower for those with eGFRs of 30–45 and below 30 mL/min per 1.73 m2, respectively.
Writing in Diabetes Care, Liakopoulos et al say this is “an important observation given that some patients with advanced renal disease could have their march toward dialysis substantially slowed” if they were to undergo gastric bypass.
The authors conclude that the “remarkable pattern of potential benefits” of gastric bypass on renal and CV outcomes in type 2 diabetes “mirror closely those of the sodium–glucose cotransporter 2 inhibitor class and add support for obesity as a key factor leading to hemodynamic stress on relevant organ systems.”
They add: “Given the advent of newer drugs that can lower weight by [approximately] 10 kg, it would be important to see how such therapies affect relevant outcomes in the future.”
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