Background: Post-bariatric surgery hypoglycemia has been previously reported. However, its prevalence remains uncertain due to variability of diagnostic criteria, types of bariatric procedures and possible lack of awareness.

Objective: To determine the frequency and severity of symptomatic and asymptomatic hypoglycemia in persons following 3 different surgical procedures ≥ 1 years before evaluation, and a group of non-operated obese persons.

Design and Setting: Observational cohort study conducted at an out-patient clinic. Fifty-one consecutive individuals were enrolled: post Roux-en-Y gastric bypass (RYGB) (n=16), post omega loop gastric bypass (OLGB) (n=12), post sleeve gastrectomy (SG) (n=15), obese persons prior to surgery (controls) (n=8). Hypoglycemic events (blood glucose ≤ 54 mg/dL) and severe hypoglycemia (blood glucose ≤ 40 mg/dL) were evaluated by: symptoms' questionnaire, mixed meal tolerance test (MMT) and continuous glucose monitoring (CGM).

Results: According to questionnaires, meal-related complaints were reported in 11 (26%) of the surgical group and 1/8 of controls. During MMT, 88%, 82% and 67% experienced hypoglycemia in the RYGB, OLGB and SG groups respectively, vs. none in the controls (P < 0.001). Severe hypoglycemia occurred in 38%, 45% and 7% of the RYGB, OLGB and SG groups respectively, (P= 0.025) but only 10 of the total operated group (24%) reported any symptoms. During CGM, fasting hypoglycemic events occurred more in the RYGB and OLGB vs. the SG group: 55%, 63% vs.17% respectively, (P= 0.036).

Conclusions: Post-bariatric surgery hypoglycemia is a very common phenomenon after 3 types of bariatric surgery and can be severe especially following bypass procedures. Intriguingly, our results show that hypoglycemia occurs not only in postprandial but also in fasting state, especially following bypass procedures. In many cases there were no specific complaints that may lead to underestimation of this serious complication.


H. Knobler: Advisory Panel; Self; AstraZeneca, Novo Nordisk A/S. L. Lazar: None. S. Sapojnikov: None. G. Pines: None. E. Mavor: None. V. Ostrovsky: None. T. Schiller: Advisory Panel; Self; Novo Nordisk Inc., Sanofi-Aventis. T. Zornitzki: None.

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. More information is available at