MON-183 Comparison of Continuous Glucose Monitor versus Meal Tolerance Test for Detection of Post-Bariatric Surgery Hypoglycemia

Objective: Post-bariatric surgery hypoglycemia (PBH) is an emerging metabolic complication thought to be due in part to an exaggerated insulin response to a meal. We sought to compare the ability of continuous glucose monitor (CGM) versus meal tolerance test (MTT) in detecting PBH. Methods: Among the participants who underwent bariatric surgery at our institution and completed the hypoglycemic symptoms (hypo-sx) survey, we enrolled 20 Roux-en-Y gastric bypass (RYGB, 10 with and 10 without hypo-sx) and 21 sleeve gastrectomy (SG, 10 with and 11 without hypo-sx) patients. Participants wore the CGM (Dexcom, San Diego, CA) for 72-120 hours at home and additionally underwent a MTT during a research visit. Hypoglycemia was defined as postprandial (within 5 hours of eating) interstitial or plasma glucose <55 mg/dl on CGM or MTT. We used Chi-square test to compare the difference in hypoglycemia detected by CGM alone vs CGM and MTT. Results: A total of 41 participants completed both the CGM and MTT on average 5.5 years since surgery, with mean age of 51 years, mean preoperative BMI of 49 kg/m(2), 81% female, 61% Caucasian, 51% post SG, ; 49% had high suspicion for hypoglycemia on prior hypo-sx survey. Of those, 22 participants (54%) had postprandial hypoglycemia on CGM versus 10 (24%) on MTT. Only 4 participants reported hypo-sx during MTT. Compared to the 8 participants who had hypoglycemia on both tests, the 14 participants who had postprandial hypoglycemia on CGM only were similar in clinical characteristics including age, gender, ethnicity, type of surgery, time since surgery, hypo-sx survey response and preoperative BMI. Conclusions: Asymptomatic postprandial hypoglycemia was common in post-bariatric patients regardless of surgery type and previous response to hypo-sx survey. Assessments that rely on hypoglycemic symptoms or MTT may not adequately capture PBH. Future studies should consider CGM to assess the true prevalence and impact of PBH.