Objective To investigate the influencing factors of the outcomes after metabolic and bariatric surgery in patients with type 2 diabetes mellitus (T2DM) complicated by obesity.

Methods A total of 89 patients with T2DM complicated by obesity who underwent metabolic and bariatric surgery were selected as the study subjects. Routine follow-up was conducted for 12 months postoperatively, and they were divided into good outcome group (61 cases) and poor outcome group (28 cases) according to the Bariatric Analysis and Reporting Outcome System (BAROS). Enzyme-linked immunosorbent assay (ELISA) was used to detect gastrointestinal peptide hormones, including human cholecystokinin (CCK), insulin, glucagon-like peptide-1 (GLP-1), leptin, human ghrelin and peptide YY. Multivariate logistic regression analysis was employed to screen for the influencing factors of postoperative outcomes. Receiver operating characteristic (ROC) curve was drawn to evaluate the predictive efficacy of baseline serum leptin combined with CCK for the outcomes of metabolic and bariatric surgery in patients with T2DM complicated by obesity.

Results The baseline body mass index (BMI), waist circumference, baseline glycosylated hemoglobin (HbA1c) and homeostasis model assessment of insulin resistance (HOMA-IR) in the poor outcome group were significantly higher than those in the good outcome group (P < 0.05). The baseline and 1-month postoperative levels of insulin, leptin, human ghrelin and CCK in the poor outcome group were significantly lower than those in the good outcome group, while the GLP-1 level was significantly higher than that in the good outcome group (P < 0.05). In the good outcome group, the 1-month postoperative levels of insulin, leptin, human ghrelin and CCK were significantly higher than the baseline levels, while the GLP-1 level was significantly lower than the baseline level (P < 0.05). Baseline BMI, baseline HOMA-IR, baseline leptin and baseline CCK were influencing factors for postoperative outcomes (P < 0.05). The area under the curve (AUC) of serum baseline leptin combined with CCK for predicting the poor effect of bariatric metabolic surgery in patients with T2DM and obesity was 0.806, which was greater than that predicted by each index alone (P < 0.05). The sensitivity and specificity of the prediction by baseline serum leptin combined with CCK were 83.6% and 77.4%, respectively.

Conclusion Elevated baseline BMI and HOMA-IR values, as well as decreased baseline leptin and CCK levels, may indicate poor outcomes after metabolic and bariatric surgery in patients with T2DM complicated by obesity.