This study was designed to investigate the factors correlated with long-term weight loss and DM remission after LSG. The factor correlated with a %EWL ≥ 50% 3 years post-operation was a better %EWL at 1 year post-operation. Regarding the factors correlated with DM remission at 3 years post-operation, a low preoperative NLR and DiaRem score and CR or PR at 1 year post-operation were identified.
An SG, in which 80% of the stomach is removed together with the greater curvature but with the intestinal anatomy unchanged, has been gaining in popularity. An SG is considered as a definitive procedure to treat morbid obesity and obesity-related diseases. The number of SGs has been increasing in many countries [19–21], being successfully performed by laparoscopy in 99.7% of cases, with relative safety [22].
The resolution rates of obesity-related diseases in LSG were reported as 58.6% for diabetes, 38.8% for HT, 63% for HL, and 91.2% for SAS [23].
Regarding predictors of postoperative weight loss after LSG, Seki et al. reported that the %EWL in the super morbid obesity group (BMI ≥ 50 kg/m2) was significantly lower than that in the mild obesity group(BMI < 35 kg/m2) and reference groups (35 kg/m2 ≤ BMI < 50 kg/m2) [11]. The ABCD score is a well-established predictor of the success of T2DM treatment after LSG. In this report, the authors would only recommend LSG for the T2DM patients with an ABCD > 4 [10]. However, the preoperative BMI and ABCD score displayed no relationship with T2DM resolution or postoperative weight loss in the authors’ study. In that study, the factor correlated with a %EWL ≥ 50% at 3 years post-operation was a better %EWL at 1 year post-operation. Regarding the factors correlated with DM remission at 3 years post-operation, a low preoperative NLR and DiaRem score and CR or PR at 1 year post-operation were identified.
The NLR was reported to be a marker of intestinal inflammation because it reflects changes in the gut microbiota [24]. Therefore, the preoperative NLR may reflect preoperative intestinal and systemic inflammation and contribute to postoperative weight loss and T2DM resolution by LSG.
The DiaRem score is a novel preoperative method to predict the probability of T2DM remission after Roux-en-Y gastric bypass surgery [17]. In validation sets, the predicted probabilities for the 5-year DiaRem score probability were: DiaRem 0–2 (88–99%), 3–7 (64–88%), 8–12 (23–49%), 13–17 (11–33%), and 18–22 (2–16%).
In our data, the accomplishments of a %EWL ≥ 50% and CR or PR of DM at 1 year post-operation were important for the long-term effect after LSG.
Regarding long-term weight loss after LSG, a better weight loss at 1 year post-operation was important. In terms of long-term DM remission, a low preoperative NLR and DiaRem score and the accomplishment of CR or PR at 1 year post-operation were key factors.