Glycemic Patterns Are Distinct in Post-Bariatric Hypoglycemia after Gastric Bypass (PBH-RYGB)

Abstract

Context: Severe hypoglycemia with neuroglycopenia, termed post-bariatric hypoglycemia (PBH). typically occurs postprandially, but it is also reported after activity or mid-nocturnally. Objective: To quantify glycemia, glycemic variability, and magnitude/duration of low sensor glucose (SG) values in patients with PBH after Roux-en-Y gastric bypass (PBH-RYGB). Methods: This retrospective analysis of data from an academic medical center included individuals with PBH-RYGB (n=40), reactive hypoglycemia without gastrointestinal surgery (Non-Surg Hypo, n=20), prediabetes (Pre-DM, n=14), newly diagnosed T2D (n=5), and healthy controls (HC, n=38). Masked continuous glucose monitoring (Dexcom G4) was used to assess patterns over 24 hours, daytime (6 am-midnight) and nighttime (midnight-6 am). Prespecified measures included mean and median SG, variability, and percent time at thresholds of sensor glucose. Results: Mean and median SG were similar for PBH-RYGB and HC (mean: 99.8±18.6 vs 96.9±10.2 mg/dL; median: 93.0±14.8 vs 94.5±7.4 mg/dL). PBH-RYGB had a higher coefficient of variation (27.3±6.8 vs 17.9±2.4%, P<0.0001) and range (154.5±50.4 vs 112.0±26.7 mg/dL, P<0.0001). Nadir was lowest in PBH-RYGB (42.5±3.7 vs HC 49.0±11.9 mg/dL, P=0.0046), with >2-fold greater time with SG<70 mg/dL vs HC (7.7±8.4 vs 3.2±4.1%, P=0.0013); these differences were greater at night (12.6±16.9 vs 1.0±1.5%, P<0.0001). Non-Surg Hypo also had 4-fold greater time with SG<70 at night vs HC (SG<70: 4.0±5.9% vs 1.0±1.5%), but glycemic variability was not increased. Conclusion: Patients with PBH-RYGB experience higher glycemic variability and frequency of SG<70 compared to HC, especially at night. These data suggest that additional pathophysiologic mechanisms beyond prandial changes contribute to PBH.