Was it the Diet or the Surgery?   (April 25, 2013)

A recent study, Rapid Improvement of Diabetes After Gastric Bypass Surgery, Is It the Diet or Surgery? caught my eye. As long-term readers know, I’ve been an adamant advocate for limiting the use of weight loss surgery for diabetes management to patients participating in clinical trials (see Weight-Loss Surgery Does Not Cure Diabetes).

In the recent study, ten patients with T2DM who were planning to undergo weight loss surgery -- technically, the surgery was a Roux-en-Y gastric bypass procedure -- were followed in a prospective trial, done in an inpatient setting during two separate 10-day periods.

In the first study period, the participants were treated only by eating the standard pre-op and post-op diet that is given to patients undergoing bariatric surgery. They even had a day with only intravenous fluids, without any oral intake, to mimic the day of surgery.

Later, after six weeks or more, the patients received the bariatric surgery and followed the same diet (in what  was called the second study period). The authors state that the only difference between the two study periods was the performance of the surgery on day 3 and an X-ray study of the gut using Gastrografin performed during the morning of day 4.

During both the study periods, the researchers measured blood glucose levels every four hours, as well as other testing, to determine the impact of the diet. The results were fascinating: there was more improvement in overall glucose control in the first study period, with the dietary intervention alone, than after bypass surgery!

The authors point out that their findings “support the hypothesis that rapid diabetes resolution after RYGB is mediated by caloric restriction.” This completely undercuts the theory that the weight-loss-surgery magically causes immediate improvement in diabetes, which has been promoted in on-line statements such as “Days after undergoing gastric bypass surgery, [name deleted]’s diabetes was gone.”

As the author indicate, their study implies that severe dietary interventions have the potential to resolve diabetes to a comparable degree as surgery. It all boils down to a simple question: whether patients would be willing to undergo the stringent dieting while skipping the surgery.