It seems that weight-loss surgery to treat diabetes isn’t quite as efficacious as some of its proponents might wish. In a recent study, A Multisite Study of Long-term Remission and Relapse of Type 2 Diabetes Mellitus Following Gastric Bypass, the authors reviewed records of 4,434 adults with uncontrolled or medication-controlled type 2 diabetes who had gastric bypass from 1995 to 2008 in three US centers. The definition used for complete diabetes remission as “co-occurrence of: (1) diabetes medication discontinuation and (2) fasting glucose values <100 and/or HbA1c levels <6.0 % occurring ≥90 days after the end of the last filled diabetes medication prescription.” Relapse was defined as “one or more of the following conditions: (a) restarting diabetes medication; (b) one or more HbA1c measures ≥6.5 %; and/or (c) one or more fasting glucose measures ≥126 mg/dL.”
This kind of study, looking at records from prior surgery, is called “retrospective” and is subject to errors in selection and follow-up that can be eliminated by setting up studies in advance and watching what happens (“prospective” studies). But it’s a start, especially as a large number of patients could be reviewed fairly rapidly to see what trends might be seen.
The results showed that about two-thirds (68.2%) of the patients had complete type 2 diabetes remission over 5 years. This reported rate is lower than earlier studies, and the authors attributed the smaller percentage to their using a more stringent (and in my opinion, more appropriate) A1C standard.
But over a third (35.1%) of subjects who had initial complete remission of their diabetes after surgery experienced a relapse within 5 years, leading the authors to comment that “Contrary to some published opinions, our current study indicates that many patients do not experience a durable remission of type 2 diabetes after bariatric surgery.”
Not surprisingly, they found that patients who never completely remitted their diabetes lost less weight than those who achieve complete remission. However, the data also yielded “some surprising and provocative results” -- they found a slight trend towards relapsing patients having more durable weight loss over time. “This finding is counter-intuitive and deserves further confirmation in other samples.”
They found that patients treated with insulin were less likely to remit and more likely to relapse than those not on insulin prior to surgery. But not all patients receiving insulin fail to remit their diabetes, and they suggested that further research is needed to determine whether the outcomes from bariatric surgery for patients who experience early initiation of insulin therapy are different from those who had long delays before starting insulin.
They also found that worse preoperative glycemic control and longer duration of diabetes were associated with lower remission rates and higher relapse risk.
The author’s conclusions? First: Patients should be counseled that bariatric surgery alone does not reliably “cure” diabetes. Second: the data suggested that the effect of bariatric surgery on durable diabetes remission is likely to be strongest among those who are earlier in the course of their diabetes.
And their final comment was a plea for future prospective, randomized controlled studies. As I’ve said several times before*, this is still experimental surgery: we don’t know long-term outcomes, and only scientific study will answer the questions as to the place of bariatric surgery in patients with diabetes.
In the meantime, I continue to feel strongly that any person with diabetes who might be contemplating weight-loss surgery should be enrolled in a study that's well-designed, and which has appropriate staff at the study site to assist with perioperative problems, and where you as the patient sign an "Informed Consent Form" (ICF) that you know that you are participating in a study. Realize that this is experimental surgery, even if short-term improvement of diabetes is likely. And as such, it remains my opinion that this surgery should only be undertaken in a clinical trial setting, with a highly qualified team, and appropriate safeguards in place.