Reported incidences of HH range from 0.2 to 1% after RYGB and is observed after gastric bypass procedures only. In HH plasma glucose concentrations reach values below 50 mg/dL (2.8 mmol/L) and adrenergic and neuroglucopenic symptoms occur, often occurring after a meal. After a meal or glucose challenge an early large glucose peak followed by an insulin peak is observed in HH patients. Additionally, an increased postprandial GLP1 level compared to RYGB controls without HH was observed. Low plasma glucose levels are also found in asymptomatic patients after RYGB in 30 to 50% of the patients.