To investigate the clinical efficacy of the laparoscopic Roux-en-Y gastric bypass (LRYGB) and metformin in the treatment of obese patients with type 2 diabetes mellitus, and influencing factors of remission rate of diabetes.

The case-control study was conducted. The clinical data of 172 obese patients with type 2 diabetes mellitus who were admitted to the First People′s Hospital of Shangqiu (43 patients) and the First Affiliated Hospital of Sun Yat-sen University (129 patients) from June 2010 to June 2015 were collected. Of 172 patients, 82 undergoing LRYGB were allocated into the group A and 90 taking oral metformin were allocated into the group B. Observation indicators: (1) follow-up situations; (2) comparison of metabolic indices after treatment between the 2 groups; (3) influencing factors analysis of remission rate of diabetes in patients undergoing LRYGB; (4) influencing factors analysis of remission rate of diabetes in patients taking oral metformin. Follow-up using outpatient examination and telephone interview was performed to detect occurrence of treatment-related complications up to January 2017, and metabolic indices were measured regularly. Measurement data with normal distribution were represented as ±s and comparison between groups was analyzed using the independent-sample t test. Repeated measurement data were analyzed by the repeated measures ANOVA. Comparisons of count data were evaluated by the chi-square test. The univariate analysis and multivariate analysis were respectively done using the chi-square test and Logistic regression model.

(1) Follow-up situations: 172 patients were followed up after treatment for 19-43 months, with a median time of 28 months. During the follow-up, 5 patients complicated with mild diarrhea and 1 complicated with iron deficiency anemia at 1 year postoperatively were improved by symptomatic treatment in the group A, and there was no treatment-related complications in the group B. (2) Comparison of metabolic indices after treatment between 2 groups: body mass, BMI, 2-hour postprandial blood glucose (2HPBG), 2-hour postprandial serum C-peptide, glycosylated hemoglobin (GHb), fasting insulin, 2-hour postprandial insulin (2HPI), low-density lipoprotein (LDL) and cases with hypertension in the group A were (89±6)kg, (31.5±2.0)kg/m², (19.4±3.9)mmol/L, (3.52±0.32)μg/L, 15.7%±5.3%, (8.0±1.4)uIU/L, (20.6±2.5)uIU/L, (3.7±1.3)mmol/L, 24 before LRYGB and (77±16)kg, (24.2±2.9)kg/m², (10.6±2.6)mmol/L, (7.19±2.23)μg/L, 5.3%±4.5%, (9.2±4.3)uIU/L, (28.3±2.9)uIU/L, (2.2±2.1)mmol/L, 9 after LRYGB, respectively, with statistically significant differences between preoperative and postoperative indicators (F=2.112, 3.026, 1.253, 2.107, 1.257, 3.473, 1.223, 2.584, χ²=8.540, P<0.05). Fasting blood glucose, 2HPBG, fasting serum C-peptide, 2-hour postprandial serum C-peptide, GHb, fasting insulin and 2HPI in the group B were (11.3±2.5)mmol/L, (18.5±4.4)mmol/L, (1.54±0.33)μg/L, (3.57±0.91)μg/L, 17.5%±8.0%, (8.2±1.3)uIU/L, (21.2±2.6)uIU/L before taking oral metformin and (6.6±1.1)mmol/L, (10.2±2.8)mmol/L, (3.52±1.34)μg/L, (7.68±1.94)μg/L, 5.4%±2.1%, (9.6±3.9)uIU/L, (30.3±3.1)uIU/L after taking oral metformin, respectively, with statistically significant differences between before and after taking oral metformin (F=1.245, 3.224, 3.127, 2.064, 3.672, 2.074, 1.137, P<0.05). Remission rate of diabetes and excess weight loss (EWL) in patients after treatment were 14.6%, 80%±15% in the group A and 11.1%, 60%±10% in the group B, respectively. There were statistically significant differences in body mass, BMI and EWL after treatment between the 2 groups (t=1.973, 2.326, 2.347, P<0.05), and no statistically significant difference in remission rate of diabetes between the 2 groups (χ²=0.477, P>0.05). (3) Influencing factors analysis of remission rate of diabetes in patients undergoing LRYGB: the results of univariate analysis showed that BMI, diabetes duration and LDL were factors affecting remission rate of diabetes in patients undergoing LRYGB, with statistically significant differences (χ²=11.267, 9.519, 5.567, P<0.05). The results of multivariate analysis showed that diabetes duration<10 years was an independent factor affecting good remission rate of diabetes in patients undergoing LRYGB, with statistically significant differences [OR=2.202, 95% confidence interval (CI): 1.418-3.420, P<0.05]. (4) Influencing factors analysis of remission rate of diabetes in patients taking oral metformin: the results of univariate analysis showed that diabetes duration, GHb and LDL were factors affecting remission rate of diabetes in patients taking oral metformin, with statistically significant differences (χ²=6.306, 7.758, 4.652, P<0.05). The results of multivariate analysis showed that GHb <15.0% was an independent factor affecting good remission rate of diabetes in patients taking oral metformin, with statistically significant differences (OR=3.167, 95%CI: 1.586-6.325, P<0.05).

LRYGB and oral metformin in the treatment of obese patients with type 2 diabetes mellitus are safe and effective, showing an equivalent remission rate of diabetes, and LRYGB had an advantage of weight loss. Diabetes duration <10 years and GHb <15.0% are respectively independent factors affecting good remission rate of diabetes in patients undergoing LRYGB and taking oral metformin.

Obesity; Diabetes mellitus, type 2; Gastric bypass; Metformin; Laparoscopy