Lent et al. (1) report on mortality in patients with and without diabetes undergoing gastric bypass or medical treatment. After a mean follow-up period of 5.8 years, they show that the benefit of gastric bypass versus medical treatment is confined to patients with diabetes.
A few articles, analyzed in a meta-analysis by our group (2), have shown that long-term mortality is reduced with bariatric surgery in comparison with nonsurgical treatment; these studies were performed using laparoscopic adjustable gastric banding, vertical banded gastroplasty, and Roux-en-Y gastric bypass.
In spite of the statement on the appropriateness of bariatric surgery for severely obese patients with type 2 diabetes (International Diabetes Federation) (3), only three studies considered patients with diabetes, one with 100% of patients with diabetes (2), the second with 10% (2), the third with 19% (4). Only the latter study compared death rates in patients with and without diabetes (4). In contrast to the study by Lent et al. (1), after a mean follow-up period of 13.9 years, we found a similar effect of gastric banding in patients with and without diabetes (4). In addition, and this was confirmed by Davidson et al. (5), the benefit was confined to patients aged >44 years (4).
The differences in results between the two studies (1,4) might be due to several reasons: different surgical procedure, different populations, and different length of follow-up. In fact, in our study (4), Kaplan-Meier curves diverged immediately for patients with diabetes and at 10 years of follow-up in patients without diabetes.
More studies, possibly performed through other surgical procedures (biliopancreatic diversion, sleeve gastrectomy, gastric plication) and with a longer follow-up, are required to establish if bariatric surgery is effective in preventing mortality in patients without diabetes as well as patients with diabetes.
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Funding. This work was funded by Università degli Studi di Milano and Ospedale San Paolo, Milan, Italy.
Duality of Interest. No potential conflicts of interest relevant to this article were reported.
