Endocrine Abstracts

Background: Prior to gastric bypass surgery, patients undertake a 2-week low-calorie diet (LCD) of 800-1000 kcal per day. This aims to consume liver glycogen and fat stores, thereby shrinking the liver to facilitate laparoscopic access to the stomach. The impact of this diet on glycaemic control in those with type 2 diabetes has not been clearly defined.

Methodology: Seven patients with Type 2 Diabetes and obesity (mean age 54 ± 8 years) participating in a longitudinal prospective study underwent 7-day continuous glucose monitoring (CGM) whilst on a LCD in preparation for bypass surgery. Routinely, during the diet SGLT2 inhibitors are stopped and insulin doses are reduced. Seven controls (mean age 53 ± 12 years) matched on age and pre-operative HbA1c underwent CGM whilst on their normal diet. CGM data was analysed using EasyGV Calculator v.10. Pre-diet oral hypoglycaemic and GLP1 analogue usage were similar between groups. However, four patients within controls were on insulin, compared to one patient on the diet. Results are stated as mean±SD.

Results: Average HbA1c was 62 ±10 mmol/L in the diet group vs. 61 ±9 mmol/mol in controls (P = 0.865). The average blood glucose on the diet was significantly lower at 7.8 ±1.3 mmol/L compared to 10.1 ±2.3 mmol/L in controls (P = 0.045). The diet groups spent on average 86.1% in range between 3.9 – 10.0 mmol/l, this was significantly greater than the average of 55.0% in the controls (P = 0.018). Of note, 6 of 7 patients in the diet group had TIR >70% and 4 of 7 >90%, compared to 2 and 0 in the control group, respectively.

Conclusion: For patients with diabetes and obesity, a 14-day low calorie diet represents a feasible option for rapid non-pharmacologic glycaemic control pre-operatively, that could have potential benefits throughout the whole perioperative period.