Utility of Continuous Glucose Monitoring vs Meal Study in Detecting Hypoglycemia After Gastric Bypass

Context: Gastric bypass (GB) increases postprandial glucose excursion, which in turn can predispose to the late complication of hypoglycemia. Diagnosis remains challenging and requires documentation of symptoms associated with low glucose and relief of symptom when glucose is normalized (Whipple triad). Objective: To compare the yield of mixed meal test (MMT) and continuous glucose monitoring system (CGMS) in detecting hypoglycemia after GB. Setting: The study was conducted at General Clinical Research Unit, Cincinnati Children's Hospital (Cincinnati, OH, USA). Methods: Glucose profiles were evaluated in 15 patients with documented recurrent clinical hypoglycemia after GB, 8 matched asymptomatic GB subjects, and 9 healthy weight-matched nonoperated controls using MMT in a control setting and CGMS under free-living conditions. Results: Patients with prior GB had larger glucose variability during both MMT and CGMS when compared with nonsurgical controls regardless of their hypoglycemic status. Sensitivity (71 vs 47%) and specificity (100 vs 88%) of MMT in detecting hypoglycemia was superior to CGMS. Conclusions: Our findings indicate that a fixed carbohydrate ingestion during MMT is a more reliable test to diagnose GB-related hypoglycemia compared with CGMS during free-living state.