8202 Retrospective Analysis of Mixed-Meal Testing in People with Suspected Spontaneous Post-Prandial Hypoglycemia

Abstract Disclosure: N. Sankaran: None. R. Jalleh: None. C. Bischoff: None. C. Marathe: None. Introduction: While there is no consensus on the optimal confirmatory test for postprandial hypoglycemia, guidelines suggest evaluation with a mixed meal test that is most likely to provoke symptoms of hypoglycemia as nominated by the patient. However, studies evaluating post-bariatric surgery hypoglycemia indicate that meals with a lower carbohydrate content are less likely to be associated with postprandial hypoglycemia. It is hypothesized that a greater carbohydrate load may result in an excessive second-phase insulin response resulting in hypoglycemia. We evaluated the outcomes of consecutive mixed meal tests in individuals with suspected spontaneous postprandial hypoglycemia and the relationship with the percentage carbohydrate content of the test meal. Methods: We retrospectively analysed the data of 103 unselected patients who were referred to undergo a 5-hour mixed meal test following an overnight fast, between the years 2010 - 2023 at the Royal Adelaide Hospital. Correlations were determined using a linear regression model and Student’s t-test was used to compare the mean carbohydrate meal content in those with and without postprandial hypoglycemia. Outcomes: Outcomes that were measured included post-meal blood glucose, plasma insulin, plasma C-peptide levels and the macronutrient composition of the meal. Subjective reporting of symptoms during the test were also noted and correlated with the symptoms included in the Edinburgh Hypoglycemia Score. Results: 33/103 participants were excluded as they had previously undergone islet cell transplant or bariatric surgery. Out of the remaining 70 participants referred for confirmatory MMT testing, 51 were female and 19 were male. The ages of the participants ranged from 16 to 74, with the median age of 40 years. 9 participants (6 females and 3 males) had abnormal results with glucose below 3.0mmol/L. 34 participants experienced hypoglycemia with glucose levels recorded below 4.0mmol/L during the test. There was no difference in carbohydrate content consumed (61.1g, P=0.30) or percentage carbohydrate (64.5%, P=0.17) in the group without postprandial hypoglycemia compared with those with postprandial hypoglycemia (carbohydrate content 67.9 g, 69.6% carbohydrate). No correlation could be identified between the percentage of carbohydrate content of the meal with the glucose nadir (P=0.75), peak insulin concentration (P=0.99) or peak C-peptide concentration (P=0.40). The percentage of carbohydrate content of the meal was neither associated with hypoglycemia (P=0.17) or symptoms (P=0.41). Conclusion: On mixed meal testing, postprandial symptoms and hypoglycemia does not correlate with either carbohydrate load or the percentage carbohydrate content of the nominated meal. Presentation: 6/1/2024