The influence of total or sub-total gastrectomy on glucose control in diabetic and non-diabetic patients

Objective. Although bariatric surgery including gastrectomy has recently emerged as a useful treatment for type 2 DM with obesity, it is not clear whether gastrectomy itself can have beneficial effects on glucose metabolism. Therefore, in this study, we investigated changes in blood glucose in patients with and without diabetes who underwent gastrectomy. Methods. From Jan 2010 to May 2014, 77 patients with diabetes and 77 patients without diabetes who underwent gastrectomy at Chonbuk National University Hospital, South Korea, were included. We compared fasting plasma glucose levels and HbA1c value before and after gastric surgery. Results. After gastrectomy, 59 patients (38.3%) showed reduced fasting plasma glucose levels at the 1 year point, and 80 patients (51.9%) exhibited reduced fasting plasma glucose at 3 years, irrespective of their diabetes status. Among 77 patients with diabetes, decreased fasting plasma glucose was observed in 22 (28.6%) and 46 patients (59.7%) 1 and 3 years after gastrectomy, respectively. In patients who exhibited reduced fasting plasma glucose after gastrectomy, the degree of reduced glucose was as follows: 56.4±48.5 vs 23.2±16.1 mg/dL after 1 year, 58.3±52.3 vs 18.4±13.7 mg/dL after 3 years, in DM and non-DM patient respectively. Conclusions. Although there was a significant drop in mean fasting glucose after gastrectomy, not all patients experienced a drop in fasting glucose. Gastrectomy did not show a consistent association with glucose reduction in patients with and without diabetes, and in about half of the patients, fasting plasma glucose levels increased after gastrectomy. Therefore, bariatric surgery including gastrectomy needs to be performed with care in diabetes, and glucose monitoring including oral glucose tolerance tests should be done for assessing or prediction of the glucose state after gastric surgery in non-DM patients.