In 2010, the international, multidisciplinary Diabetes Surgery Summit concluded with a strong consensus that bariatric surgery (now known as bariatric/metabolic or metabolic surgery) can be considered for the treatment of type 2 diabetes in patients who have body mass index ≥30 kg/m² (≥27.5 kg/m² for Asians) and glycemia inadequately controlled by medical and lifestyle therapy.

That recommendation was adopted by the American Diabetes Association (ADA) and the International Diabetes Federation, was formally ratified by 56 other leading professional societies, and was re-affirmed by the Second Diabetes Surgery Summit in 2016. Even so, few surgeons perform metabolic surgery for type 2 diabetes treatment, citing inadequate evidence, and for the same reason, many health insurance plans don’t cover it.

Long-term supportive efficacy data from the largest randomized cohort has been published in Diabetes Care. The authors are Ashley H. Vernon, MD, of the Division of General and Gastrointestinal Surgery at Brigham and Women’s Hospital, and John P. Kirwan, PhD, and Philip R. Schauer, MD, at the Cleveland Clinic, and colleagues.

Methods

Previously, four separate groups (STAMPEDE, TRIABETES, SLIMM-T2D, and CROSSROADS) initiated randomized, controlled trials that compared metabolic surgery with medical/lifestyle treatment of patients who had type 2 diabetes and overweight/obesity.

These trials included common measures and inclusion criteria, notably age 20 to 65 and BMI 27 to 45 kg/m². The trials were later harmonized to form the Alliance of Randomized Trials of Medicine versus Metabolic Surgery in Type 2 Diabetes (ARMMS-T2D), a prospective observational study.

316 patients previously randomly assigned to either surgery (N=195) or medical treatment (n=121) were analyzed. The mean age was 50, the mean BMI was 36.5 kg/m², and the mean duration of diabetes was nine years.

34% of the surgery group and 37% of the medical group had BMI <35 kg/m². In the surgery group, 55% of patients underwent Roux-en-Y gastric bypass (RYGB), 25% had sleeve gastrectomy (SG), and 20% had adjustable gastric banding (AGB).

Primary Outcome

The primary outcome was the three-year remission rate, defined per ADA consensus guidelines as achieving hemoglobin A1c levels ≤6.5% after cessation of glucose-lowering medications for at least three months:

• The rate was significantly higher in the surgery group (37.5% vs. 2.6%; P<0.001)

• When adjusted for treatment allocation, annual visit, baseline HbA1c, diabetes duration, insulin use, and sex, the predicted probability of remission at three years was 42% with surgery versus 1% with medical/lifestyle treatment (P<0.001)

Secondary Outcomes

After three years of follow-up, surgery was also significantly more efficacious on certain predetermined 3-year secondary outcomes:

• Reductions in HbA1c and fasting plasma glucose
• Reductions in BMI, body weight, and waist circumference
• Improvement in systolic blood pressure
• Improvements in high-density lipoprotein cholesterol and triglycerides
• Reduction in albumin-to-creatinine ratio
• Number of patients with metabolic syndrome
• Percentage of patients requiring medication for diabetes, dyslipidemia, or hypertension

Safety Outcomes

The cumulative serious adverse events (SAEs) through three years of follow-up included:

• Cardiovascular-related—8 in the surgery group and 16 in the medical/lifestyle group (the latter figure included one death and six angioplasty/stent procedures)

• Gastrointestinal-related—13 with RYGB, six with SG, seven with AGB and one with medical/lifestyle

• Nutrition/metabolic-related—19 with RYGB (mostly related to dehydration), four with SG, four with AGB and seven with medical/lifestyle

Conclusions

These results strongly support the efficacy and durability of metabolic surgery to treat type 2 diabetes. Enhancing the generalizability of the data compared with previous studies of metabolic surgery, 27% of the surgery group and 33% of the medical/intervention group were people of racial/ethnic U.S. minorities. There were too few AEs to draw firm conclusions about long-term safety.