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.
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.