Prevalence of hypoglycaemia in a random population after Roux-en-Y gastric bypass after a meal test

OBJECTIVE: Roux-en-Y gastric bypass (RYGB) is an effective way to induce sustainable weight loss and can be complicated by postprandial hyperinsulinemic hypoglycaemia (PHH). To study the prevalence and the mechanisms behind the occurrence of hypoglycaemia after a mixed meal tolerance test (MMTT) in patients with primary RYGB.

DESIGN: This is a cross-sectional study of patients four years after primary RYGB.

METHODS: From a total population of 550 patients, a random sample of 44 patients completed the total test procedures. A standardized mixed meal was used as stimulus. Venous blood samples were collected at baseline, every 10 minutes during the first half hour and every 30 minutes until 210 minutes after the start. Symptoms were assessed by questionnaires. Hypoglycaemia defined as a blood glucose below 3.3 mmol/L.

RESULTS: The prevalence of postprandial hypoglycaemia was 48% and was asymptomatic in all patients. Development of hypoglycaemia was more frequent in patients with lower weight at surgery (p = 0.045), with higher weight loss after surgery (p = 0.011), and with higher insulin sensitivity calculated by Homeostasis Model Assessment indexes (HOMA2-IR p = 0.014) and enhanced beta cell function (insulinogenic index at 20 minutes p = 0.001).

CONCLUSION: In a randomly selected population four years after primary RYGB surgery 48% of patients developed a hypoglycemic event during a mixed meal tolerance test without symptoms, suggesting the presence of hypoglycaemia unawareness in these patients. The findings in this study suggest that the pathophysiology of PHH is multifactorial.