Dumping syndrome (DS) is a common complication of metabolic surgery, occurring in as many as 40% of bariatric patients. The reference diagnostic test is oral glucose tolerance testing (OGTT) which is often poorly tolerated and may induce false positive results. Continuous glucose monitoring (CGM) is better tolerated and can monitor patients for about 2 weeks in everyday life. This study aimed at testing the diagnostic capacity of CGM in patients with and without DS, as validated by OGTT.

This is a retrospective monocentric study including adults after bariatric surgery, who complained of DS-compatible symptoms and who had OGTT. CGM characteristics were compared in DS-positive (n = 37) and DS-negative patients (n = 14).

None of the CGM parameters differed between the two groups: mean, variability, time in range, and time above or below range. OGTT induced different hematocrit and pulse rate responses (by DS definition) but no difference in blood glucose values.

Despite being a better-tolerated test than OGTT, CGM should not be recommended for the diagnosis of DS. It may still be useful for monitoring glucose values in everyday life to help patients modify their diet, when DS is caused by carbohydrates with high glycemic index. The reference diagnostic test for dumping syndrome is poorly tolerated and artificial. CGM is useful in everyday life, and changes in glucose might be a signal of dumping syndrome. However, CGM is not a valid diagnostic test for dumping syndrome.