Type 2 diabetes

Bariatric surgery superiority confirmed in T2D, but access still limited

Bariatric surgery is superior to medical and lifestyle therapy in many aspects of type 2 diabetes (T2D), but still only a small minority of patients have access to the treatment, researchers say.

Randomised interventional data from the largest cohort of patients to date has shown that metabolic/bariatric surgery results in much greater rates of diabetes remission (38% vs 3%) over three years and also improves glycaemic control, diabetes-related comorbidities, and weight loss compared to medical therapy.

A prospective observational study analysed data from 256 patients with T2D patients participating in the STAMPEDE, TRIABETES, SLIMM-T2D and CROSSROADS clinical trials.

Published in Diabetes Care, the study assessed outcomes in obese (mean BMI 36.5 ± 3.6 kg/m2) adults whose diabetes duration averaged 8.8 ± 5.7 years.

It showed 37.5% of those who underwent Roux-en-Y gastric bypass, sleeve gastrectomy or adjustable gastric binding achieved and maintained disease remission (HbA1c ≤ 6.5 for at least three months without usual glucose-lowering therapy) for three years versus 2.6% of medical and lifestyle therapy patients (P < 0.001).

They had larger reductions in HbA1c (𝚫 = -1.9 ± 2.0 vs -0.1 ± 2.0%, P < 0.001), fasting plasma glucose (𝚫 = -52 [-105 to -25] vs -12 [-48, 26] mg/dL, P < 0.001 and BMI (𝚫 -8.0 ± 3.6 vs -1.8 ± 2.9 kg/m2, P < 0.001), too.

“The percentages of patients using medications to control diabetes, hypertension, and dyslipidemia were all lower after surgery (P < 0.001),” the US authors noted.

“Despite growing evidence that metabolic surgery is the most effective treatment for [T2D], it is estimated that <1% of eligible patients actually undergo such operations,” they wrote.

“This is largely attributed to concerns from referring providers and patients about long-term safety and durability.”

While this study shed some light on the treatment’s durability, there were too few adverse events to draw firm, long-term safety conclusions.

However, it did note four times more cardiovascular events among medical and lifestyle patients versus surgical patients — including one death post CABG, one resuscitated cardiac arrest and several angioplasty/stent events compared with one stroke and one CABG.

Surgical patients were more likely to have gastrointestinal and nutritional-related events.

While longer and larger safety and efficacy, quality of life, biomarker and cost-effectiveness studies are still needed, the authors felt their study showed surgery was more beneficial than medical and lifestyle therapy, with “minimal and tolerable” adverse events.

Implications for Australian practice 

Speaking to the limbic, Associate Professor John Wentworth, clinician scientist at the Walter and Eliza Hall Institute said the results were not surprising and reiterated “what we’ve known [about surgery] for some time”.

Already, Diabetes Australia suggests bariatric surgery should be “more widely available” for eligible patients with T2D. It supports the procedure’s use in people with T2D and a BMI of “at least 30, where dietary, physical activity and medical interventions for obesity or diabetes have not been successful”, according to a 2021 position statement.

It noted that the surgery is a “significant commitment” and cannot be undone easily. Therefore, patients should be counselled appropriately and offered clinical and psychological support.

Treatment decisions will depend on individuals’ characteristics, “what our patients are willing to risk and how much they value a relatively quick fix from surgery compared with the more long-term approach through chronic medication, and perhaps, a more aggressive lifestyle modification to meet the same ends”, Associate Professor Wentworth said.

Finances will also play a key role, with most operations currently occurring in private practice and costs borne by patients and private insurance, he said. Any available Medicare reimbursement for bariatric surgery would only cover “a fraction of the total cost”, he added.

Associate Professor Wentworth noted that the study was conducted prior to the availability of newer medications such as GLP-1 agonists and twincretins. These are more potent for weight-loss than most of the assessed drugs (metformin, thiazolidinediones, secretagogues and incretin mimetics) and the latter will be particularly “interesting to watch as it gets rolled out in Australia”.

“I think we’re in a new era and one needs to interpret [the study’s] glycaemic results in the context of what is possible with modern medical therapy, and for that matter, more aggressive dietary therapy at diagnosis.”

Ultimately, “the aim of the game is not glucose control, it’s preventing death and preventing diabetes complications, and we still don’t really have good evidence that surgery is a better way to go compared with good medical care”, he said.

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