While bariatric surgery can improve glycemia in type 2 diabetes (T2D), it can also result in severe hypoglycemia with neuroglycopenia, termed post-bariatric hypoglycemia (PBH).  Hypoglycemia typically occurs postprandially but is also reported post-activity or mid-nocturnally.

We used masked CGM (Dexcom G4) to quantify glycemia, glycemic variability (GV), and severity/length of low sensor glucose (SG) values in patients with PBH with prior Roux-en-Y gastric bypass (PBH-RYGB, n=40), and compared patterns to those from individuals with reactive hypoglycemia without GI surgery (Non-Surg Hypo, n=20) and to public data from healthy controls (HC, n=38) and individuals with pre-diabetes (Pre-DM, n=14), and newly-diagnosed T2D (n=5). Data were assessed over 24 hours, daytime (6 AM to midnight) and nighttime (midnight to 6 AM).

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). By contrast, PBH-RYGB had a higher coefficient of variation (27.3±6.8 vs. 17.9±2.4%, p<0.0001) and wider 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 even 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 in this group.

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.

Supplementary Tables provide more information about demographics of the participants.