Clear but diminishing returns 5 years after diabetes surgery
medwireNews: The 5-year outcomes of the Diabetes Surgery Study show that the benefits of gastric bypass remain but are of smaller magnitude compared with the 1-year results.
At 1 year after surgery, 50% of type 2 diabetes patients randomly assigned to undergo Roux-en-Y gastric bypass achieved the primary combined endpoint of glycated hemoglobin (HbA1c) below 7%, low-density lipoprotein cholesterol below 100 mg/dL, and systolic blood pressure below 130 mmHg, compared with 16% in the intensive lifestyle/medical management group.
But by 5 years, the corresponding rates among the 98 patients (of an initial 120) followed up for this long had fallen to 23% and 4%, report Charles Billington (University of Minnesota, Minneapolis, USA) and co-researchers.
HbA1c levels in the surgical group gradually deteriorated; about a third of the patients who achieved 1-year HbA1c below 7% no longer met this threshold after 5 years. The proportion considered to be in remission (HbA1c <6% without antidiabetes medications) fell from 16% to 7%.
Of note, the persistent deterioration of glycemic control occurred despite patients’ weight remaining stable over years 4 and 5 of follow-up, after some increase between years 2 and 3.
This “indicates that improving diabetes control for the long-term may involve other factors, notably the health of pancreatic beta cells,” say the researchers, speculating that “[t]here may have been insufficient beta cell function in some participants to maintain long-term diabetes improvement.”
Blood pressure also increased over time, whereas cholesterol levels were similar at years 1 and 5, despite a transient increase between years 2 and 3.
The findings appear in the current issue of JAMA, which is devoted to the theme of obesity. One of the other four research reports in this issue also reports sustained diabetes remission over around 7 years of follow-up in patients who underwent surgery. The observational study shows that diabetes, originally present in 26% of the 1888 patients, remitted in 57.5% of those who opted for surgery versus 14.8% of those who chose medical treatment.
Surgical patients, 92% of whom underwent gastric bypass, also had a reduced risk for new-onset diabetes, at 0.3% versus 7.5%, with these differences significant after accounting for age, sex, and baseline BMI.
A third study, involving obese patients identified in an Israeli health fund, demonstrates the survival benefits associated with obesity surgery over around 4.5 years of follow-up. It reports 2.51 fewer deaths per 1000 person–years among the 8385 patients who underwent bariatric surgery compared with 25,155 matched patients who did not, with the mortality risk difference significant regardless of the surgical procedure used.
The final two studies looked more closely at the optimal surgical procedure; SLEEVEPASS and SM-BOSS were both randomized head-to-head studies of sleeve gastrectomy and Roux-en-Y gastric bypass. Both studies found that gastrectomy tended to be slightly less efficient than bypass, but not significantly so. In SLEEVEPASS, for example, the respective proportions of excess weight lost at year 5 were 49% versus 57%, with gastrectomy not achieving statistical equivalence to bypass, but bypass not achieving statistical superiority to gastrectomy.
The rates of diabetes remission were comparable for both procedures in both studies, although this was not a primary endpoint in either trial.
In a linked editorial, David Arterburn (Kaiser Permanente Washington Health Research Institute, Seattle, USA) and Anirban Gupta (Washington Permanente Medical Group, Seattle) describe these findings as “reassuring data to suggest that the rapid switch from Roux-en-Y gastric bypass to sleeve gastrectomy in the last decade has not been a therapeutic misadventure similar to the rise and fall of the adjustable gastric band.”
However, they highlight that new or worsening gastroesophageal reflux disease was more common after gastrectomy than bypass, and that, despite perceptions of gastrectomy as a lower-risk procedure, reoperation rates were similar after gastrectomy and bypass, but with the reasons for reoperation differing.
“There are no easy decisions, and the best procedure for each patient is the one that aligns with his or her own preferences and goals,” say the editorialists.
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