MON-LB111 Evaluation of Mixed Meal Test on the Diagnosis of Hyperinsulinemic Hypoglycemia After Bariatric Surgery

Background and aims: The physiopathology of hyperinsulinemic hypoglycemia (HH) after gastric bypass (GB) is not well understood, although it is a common adverse event after this procedure. The fast absorption of glucose after a meal, the high glucose variability, the increase in glucagon peptide 1 secretion or the hyperplasia of beta cell have been postulated as possible hypothesis. Mixed Meal Tolerance test (MMT) is used in clinical practice during HH investigation, but there is no consensus for HH diagnosis after bariatric surgery. In this scenario, we evaluated the MMT for the diagnosis of HH after GB. Material and Methods: This is an observational cross sectional descriptive study of adult (> 18 years) patients submitted to a MMT after GB from July 2016 to October 2019. 51 patients were divided in two groups: Group 1, with a history of predominantly neuroglycopenic symptoms (n = 24) and Group 2 (control) without symptoms of postprandial hypoglycemia (n= 27). The patients had no diagnosis of diabetes and weren’t using any hypoglycemic drugs. All subjects performed the MMT composed by a typical Brazilian breakfast with the following composition: 494 Kcal with 63.4% carb, 27.5% fat and 9.1% protein, in the morning after 8h fasting and blood samples (glucose, insulin, C peptide) were collected before the meal and every 30 minutes for 5 h after it. A positive test was considered if patient presents Whipple’s Triad: HH (plasma glucose was ≤ 55mg/dL with insulinemia ≥ 3 µU/mL, C peptide ≥ 0.6 ng/mL) and hypoglycemic symptoms. Statistical analysis were done using SPSS 13.0 version. Results:​ From 51 patients, 46 were female, mean age was 46.8 ± 9.2 years. 15 of the 24 patients with predominantly neuroglycopenic symptoms (Group 1) developed laboratory HH, but only 9 (37.5%) presented the Whipple’s Triad. Only one subject of the control group presented HH. All patients with neuroglycopenic symptoms during the test presented HH. From those with HH, 43% presented hypoglycemia at 90’, 50% at 120’ and 6.2% at 150’ during MMT. There were no difference between the two groups when compared the amount of weight loss neither the period of follow up after GB. Conclusion: Since all patients with neuroglycopenic symptoms during the test presented HH it might be a useful tool to exclude HH in patients with hypoglycemic symptoms after GB. This study suggests that the BMT doesn’t need to be 5h, since all of hypoglycemic episodes occur until 150’.