Background

Weight loss surgery is known to improve near-term glycemic control, lipid parameters, and body-mass index (BMI) in obese diabetics. Observational data also suggest that these improvements may translate into reduced cardiovascular disease (CVD) events. However, whether the beneficial effects of surgery are sustained over longer follow-up is relatively unknown. In this context, the Surgical Treatment and Medications Potentially Eradicate Diabetes Efficiently (STAMPEDE) investigators now report their three-year follow-up data.

Methods

STAMPEDE is a moderate-to-small size, single center, randomized study of intensive medical therapy versus weight loss surgery (gastric bypass or sleeve gastrectomy). 150 diabetic subjects were enrolled and approximately 50 assigned to each of the three intervention groups (medical therapy, gastric bypass, or sleeve gastrectomy). Importantly, this study was not blinded. Of course, blinding would have been near impossible to do, but this remains a study limitation due to the possibility of allocation bias. Also of note, study participants had very poorly controlled diabetes, with mean baseline A1c of over 9% despite half being on insulin and also an average diabetic medication use of 2.5 to 3 medications at baseline. On a positive note, investigators were able to sustain high follow-up over the 3 year study period (>90%). The primary endpoint was A1c, but a range of additional variables were also collected, including quality of life.

Results

The benefit of weight loss surgery was demonstrated to be durable and robust in this study. This benefit extended beyond the primary endpoint of A1c, to additional endpoints of BMI, triglycerides, HDL-cholesterol, and proteinuria. While LDL-cholesterol and blood pressure did not differ significantly between the groups, this was likely due to differential therapy in the study arms over follow-up (specifically the surgery group had lower need for cholesterol or BP medications over time). Also worth noting, the surgery group had higher quality of life out to 3 years, in the domains of energy/fatigue and general health. While non-blinding no doubt influenced this result, in an era of intense interest in patient-centeredness, it is encouraging that the effect of surgery on wellbeing appears to be positive.

Conclusion

The benefits of weight-loss surgery in overweight-obese, poorly-controlled, diabetics are durable. This finding should be very reassuring to referring providers and patients.

Commentary/Perspective

These data provide further encouraging evidence regarding the benefit of weight-loss surgery for those who may need it most; poorly controlled diabetics. There have been mostly anecdotal concerns that the effects of surgery on weight-loss may wane over time, however, these investigators emphatically demonstrate that weight-loss can indeed be sustained. Similarly, while it is worth emphasizing that these results may not apply to more 'typical' diabetics (with better baseline control) and that lifestyle counselling should always be emphasized first, it should also be noted that these results demonstrate surgery to be a safe and effective option in the 'real-world' (where many patients cannot lose weight with self-will alone). Of course, given this is a single center study, further findings from other groups and particularly with actual outcome data are now more necessary than ever. In addition, while the relative benefit (or harm) of gastric bypass and sleeve gastrectomy was grossly similar, this study was underpowered to determine any clinically important difference between the two surgical procedures. Similarly, whether the relatively high volume of missing values from the near 20% of individuals initially randomized to medical therapy but who withdrew from follow-up is a problem will also be informed by additional study. In summary, these findings are very encouraging and I was particularly interested to see many surgery patients remain off diabetic and other medications over time, something which should help motivate patients to lose weight (with or without surgery). Perhaps most intriguing here is the clear signal for benefit in diabetics in the 30-35 BMI range, a finding which may inform future recommendations. Specifically, 2013 AHA-ACC guidelines¹ for the management of obesity give a class IIa recommendation (level of evidence A) for bariatric surgery in persons with BMI ≥40 or those with BMI≥35 but who have obesity related complications like diabetes. However, these guidelines give no recommendation for persons <35 as evidence was not available in this setting. Thus, the results of STAMPEDE, in addition to demonstrating that durable weight loss is possible, also fill a gap in our prior understanding which may lead to new indications for weight loss surgery.

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References

1. Schauer PR, Bhatt DL, Kirwan JP, et al., on behalf of the STAMPEDE Investigators. Bariatric Surgery versus Intensive Medical Therapy for Diabetes — 3-Year Outcomes. N Engl J Med 2014;Mar 31:[Epub ahead of print].
2. Schauer PR, Kashyap SR, Wolski K, et al. Bariatric Surgery versus Intensive Medical Therapy in Obese Patients with Diabetes. N Engl J Med 2012; 366:1567-1576.
3. Jensen MD, Ryan DH, Apovian CM, et al. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults: A report of the american college of cardiology/american heart association task force on practice guidelines and the obesity society. J Am Coll Cardiol 2013. [Epub Ahead of Print].

Keywords: Bariatric Surgery, Blood Glucose, Body Mass Index, Cardiovascular Diseases, Diabetes Mellitus, Lipids, Obesity, Weight Loss

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