There is a rapidly growing interest in metabolic surgery for the treatment of type 2 diabetes. However, its efficacy in the non-morbidly population is not clear yet and the underlying mechanism remains elusive.

Meanwhile, the incidence of early gastric cancer (EGC) in Korea has gradually increased, the long-term quality of life of the patients with EGC has become an important issue. Since the reconstruction methods after gastric cancer surgery are similar to that of metabolic surgery, some surgeons have attempted to modify the reconstruction methods after standard radical gastrectomy to achieve better glycemic control in gastric cancer patients with type 2 diabetes.

The present study aimed to investigate the changes in glucose metabolism and incretin hormone responses following different types of reconstruction after distal gastrectomy in non-morbidly obese gastric cancer patients with type 2 diabetes. This is a non-randomized, prospective, single-center, phase II pilot study.

Patients diagnosed with stage I gastric cancer and type 2 diabetes are eligible for the present study. Patients who will undergo laparoscopic distal gastrectomy for cancer located at the lower two-thirds of the stomach will only be included. The reconstruction method will be selected among conventional Billroth I, long-limb Billroth II (with 100 cm-long biliopancreatic limb), or long-limb Roux-en-Y (with 100 cm-long Roux limb) reconstruction methods according to the surgeon's preference as well as the size of the remnant stomach. All the patients are subjected to a 75g-oral glucose tolerance test (OGTT) preoperatively, and at 5 days, 3 months, 6 months postoperatively and serum glucose, as well as incretin hormones, will be serially measured.

Inclusion Criteria:

• Patients diagnosed with type 2 diabetes as well as pathologically proven gastric cancer of clinical stage I according to the AJCC 7th edition
• Those who are expected to undergo laparoscopic distal gastrectomy
• Body mass index < 30 kg/m2

Exclusion Criteria:

1. baseline fasting C-peptide level < 1.0 ng/dL (who had the possibility of type 1 diabetes)
2. previous radiotherapy or surgery at upper abdomen other than laparoscopic cholecystectomy
3. other malignancies in recent 5 years
4. vulnerable patients (pregnant women, those with cognitive impairment, etc)
5. ECOG-PS ≥ 2
6. participating in other clinical trials within 6 months