While bariatric surgery can promote remission of type 2 diabetes (T2D), it can also result in severe hypoglycemia, termed post-bariatric hypoglycemia (PBH). Hypoglycemia is most often recognized after meals, but also can occur after activity or during mid-nocturnal hours and can yield unawareness and disabling neuroglycopenia.

We used blinded CGM (Dexcom G4) to characterize glycemia, glycemic variability (GV), and severity and length of hypoglycemia in patients with PBH with prior roux-en-Y gastric bypass (PBH, n=40). We compared results to those of individuals with reactive hypoglycemia with no prior GI surgery (Hypo, no-GS, n=20) and to publicly available Dexcom G4 data from 3 additional groups: healthy controls (HC, n=38), prediabetes (Pre-DM, n=14), and T2D (n=5). Metrics were assessed over 24 hours as well as during daytime (6 AM to midnight) and nighttime (midnight to 6 AM) independently.

Mean and median sensor glucose (SG) were similar for PBH 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, p>0.05 for both). By contrast, PBH had higher coefficient of variation (27.3±6.8 vs. 17.9±2.4%, p<0.0001) and a wider range and IQR of SG values (range: 154.5±50.4 vs. 112.0±26.7 mg/dL; IQR: 28.0±7.4 vs. 20.0±4.4, p<0.0001 for both). Nadir SG was lowest in PBH (42.5± 3.7 mg/dL vs. other groups, p<0.0001) with statistical significance vs. HC (49.0±11.9 mg/dL, p=0.0046). PBH had greater percentage of time with SG<70 mg/dL vs. HC (7.7±8.4 vs. 3.2±4.1%, p<0.002); these differences were greater at night (12.6±16.9 vs. 1.0±1.5%, p<0.0001). Also, the frequency of severe hypoglycemic episodes (<54 mg/dL, duration ≥ 15 minutes) per day was higher for PBH group vs. HC (0.5 vs. 0.1, p<0.002).

In summary, patients with PBH experience higher GV and greater severity and frequency of hypoglycemia compared to HC, especially at night. Future studies should explore the potential of CGM technology in assisting PBH patients to recognize early hypoglycemia and prevent severe hypoglycemia.


D. Lee: None. J. Dreyfuss: None. C.M. Mulla: None. M. Patti: Consultant; Self; Fractyl Laboratories, Inc. Research Support; Self; Dexcom, Inc., Xeris Pharmaceuticals, Inc. Other Relationship; Self; Academy of Nutrition and Dietetics, American Diabetes Association, American Society of Metabolic and Bariatric Surgery, Endocrine Society, Insulet Corporation, King Abdullah International Medical Research Center, SUNY Downstate.


National Institutes of Health (R01DK121995); National Institute of Diabetes and Digestive and Kidney Diseases (T32DK007260)

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