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Page 4 of 7 Veilleux et al. Mini-invasive Surg 2020;4:4 I http://dx.doi.org/10.20517/2574-1225.2020.01

While duodenal switch and bypass may trend toward the most optimal outcomes [7,14] , for a patient with
advanced diabetes of long duration, the β-cell reserve of the pancreas is likely minimal and incapable
[19]
of improving significantly regardless of the chosen operation. To further evaluate this, Aminian et al.
examined a large cohort (n = 900) of patients in order to create the individualized metabolic surgery score.
This score, which uses previously discussed preoperative risk factors for resolution of diabetes (duration,
HbA1C, number of oral medications, and insulin use), categorizes T2DM into three stages of severity. What
this score highlights is that in patients with severe T2DM (Diabetes > 10 years, multiple oral antidiabetic
drugs + insulin, and HbA1C of 8%), both sleeve and bypass have similarly poor efficacy in diabetes
improvement (12% long-term remission for both) [10,19] . Thus, there is little evidence that choosing bypass
over sleeve in this group of patients will lead to improved glycemic outcomes, and the most clinically safe
procedure is likely the best choice. Similarly, yet at the other end of the spectrum, for patients with diabetes
of minor severity, the cohort was observed to have high rates of diabetes remission at long-term follow up
[19]
with both sleeve (74%) and bypass (92%) . Thus, while bypass had slightly higher rates of remission, the
patient should be counseled that sleeve is also a very efficacious option. It is in the intermediate patients
with moderate severity diabetes where bypass was observed to have significantly improved outcomes
compared to sleeve. This difference is much more likely to be of clinical importance when choosing
procedure. In the intermediate group, 60% of patients who underwent gastric bypass showed long-term
[19]
diabetes remission compared to 35% of those who had sleeve gastrectomy .

Recognizing the above when planning with the patient will help to set appropriate expectations for disease
response in the postoperative period. Additionally, given that many patients with severe diabetes may
also be poor operative candidates, it is important to remember that their metabolic response from sleeve
gastrectomy is likely to be the same as with an anastomotic procedure, potentially allowing for a quicker
and thus safer surgery. To avoid choosing a more advanced procedure for a patient who may not benefit
from improved outcomes, it is important to consider the degree of their β-cell reserve and thus potential
for improvement.

REVISIONAL SURGERY
Although many studies focus their investigation on the sustained remission of diabetes, we should not
consider relapse a failure of treatment. Many patients with relapse still experience the benefit of improved
[20]
glycemic control/A1C while requiring fewer medications . However, similar to obesity, diabetes is a
[7]
chronic illness that requires a long-term strategy for treatment. Mingrone et al. found that, at five years,
hyperglycemia relapsed in 44% of the 34 surgical patients who had achieved two-year remission (however,
they maintained a mean HbA1c of 6.7). As follow up time increases, the proportion of patients who
maintain diabetes remission decreases [6,21] and further options for treatment must be considered. Just as we
are increasingly recognizing revisional surgery as a necessary approach for patients who obtain inadequate
results in the treatment of their obesity, a similar approach will likely hold true for diabetes.

The current data however do not support adequate analysis of a revisional approach. Studies have typically
evaluated whether patients remain in remission at a defined follow up period. This has mainly allowed for
comparison on the efficacy between procedures at five years or more. However, if we consider total number
of remission years obtained, we may find that a combination of procedures yields greater lifetime remission
than any primary procedure alone. We have a paucity of evidence regarding the role of revisional surgery
in the treatment of T2DM [20,22] . In a review of multiple studies on revisional bariatric surgery, Yan et al.
[23]
demonstrated that, in the majority of cases, reoperation has a positive effect on both improvement in
diabetes and further weight reduction. Unfortunately, these observational studies were of rather low
[23]
power, without investigation of diabetes being the primary end point . We have yet to evaluate with high-
powered studies if the total years of diabetes improvement can be maximized with a stepwise approach.