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Yang et al. Mini-invasive Surg 2021;5:11 I http://dx.doi.org/10.20517/2574-1225.2021.06 Page 9 of 12

for remission and the timing of evaluation may affect the results. In the present study, using strict criteria,
remission was observed in 19.7%, but near-remission was observed in the remaining 80.3% of the patients.
Of note, LOCF had to be used to account for missing values in many patients.

Nevertheless, this study confirms the results of other work on the effectiveness of RYGB for weight loss
in China and contributes to the growing body of evidence that RYGB can slow the progression of weight-
related diabetes, even inducing remission in some and improving control with fewer AHAs in the vast
majority. Notably, more than half of those on insulin at baseline achieved glycemic control without insulin
at 12 months after RYGB surgery. Preventing or reducing the need for insulin treatment is important both
[20]
from a patient’s quality of life perspective and from a healthcare utilization perspective . In the present
study, RYGB allowed at least a partial remission in all patients. Those with a short T2DM duration were
at a higher likelihood of achieving remission, while those with a longer duration can nevertheless obtain
some benefits from RYGB. Previous studies generally agree that younger age, shorter duration of diabetes,
higher C-peptide levels, higher baseline BMI, and higher baseline visceral fat area are associated with
remission after surgery [21-30] . Three prediction models based on different combinations of those variables are
available (the DiaRem, ABCD, and individualized metabolic surgery scores) [21,31-33] . In the present study, no
score could be derived from the data because of the limited data, but age and T2DM duration were lower
and baseline BMI and weight were higher in the remission group than in the non-remission group, as
supported by the previous models [21,31-33] and studies [21-30] . Nevertheless, patients with higher BMI at baseline
had a higher probability of achieving remission than those with a lower BMI. There is currently no accepted
explanation for this phenomenon, but there is the possibility that the disease characteristics (such as insulin
[21]
resistance and other metabolic disturbances) are different between the two groups of patients . This
will have to be examined using metabolic studies to determine possible differences in energy metabolism
among patients that could account for the differences in weight loss. Because the BMI cutoff points are not
the same between Chinese and Western patients, it is possible that the percent change in excess weight loss
(%EWL) is also different. In the present study, the %EWL was -42.8% ± 44.2%, indicating that, although
the excess weight was cut by half in most patients, there was a wide variability among patients. In addition,
%EWL was not associated with remission, while some previous Western studies associated %EWL with
remission [11,23] . A meta-analysis showed ethnic differences in %EWL after metabolic surgery, although Asian
patients were not included . In addition, around 60% of the patients in this study had a BMI lower than
[34]
2
32.5 kg/m , which may be very different from Western populations.
In the present study, the operative time and length of stay were longer than those usually observed in
Western countries. The present study covered the 2009-2014 period, and Du et al. showed that, even
[5]
though bariatric surgery has been performed in China since 2001, most of the cases were in the 2011-2015
period, suggesting that the experience during 2009-2014 was relatively low, leading to longer surgeries.
Regarding the length of stay, there is a shortage of general practitioners in China, and the Chinese
healthcare system is based on specialists . Therefore, patients are generally discharged when all symptoms
[35]
and signs are resolved, leading to longer lengths of stay.

STRENGTHS AND LIMITATIONS
The strength of this report is the multicenter approach of data collection, capturing data from five Chinese
[12]
hospitals. This report provides one of a limited number of multicenter studies available from China .
This study has several limitations, including the retrospective design, no comparative arm, a single
procedure (RYGB) evaluated, exclusion of patients without 12-month data, a small patient population, lack
of complete outcome data reported on the majority of patients at 12 months (e.g, BMI values were only
available in 78 out of 103 T2DM subjects), and the short-term follow-up. The data were from the first sites
in China that conducted RYGB surgery, and it took time for patients to accept the new treatment pathway.