Continuous glucose monitoring in the management of patients after gastric bypass

In patients with gastric bypass (GB), high glucose variability (GV) and hypoglycemia have been demonstrated, which could impact the metabolic status and eating behavior. We describe the glucose patterns determined through continuous glucose monitoring (CGM) in two patients with >5 years follow-up after GB and significant weight recovery, who reported hypoglycemic symptoms that interfered with daily activities, and their response to a nutritional and psycho-educative prescription. Case 1: A 40-year-old woman without pre-surgical type 2 diabetes (T2DM) and normal HbA1c, in whom CGM showed high GV and hypoglycemic episodes that did not correlate with the time of hypoglycemic symptoms. Her GV reduced after prescription of a diet with low glycemic index and modification of meal patterns. Case 2: A 48-year-old male with pre-surgical diagnosis of T2DM and current normal HbA1c, reported skipping meals. The CGM showed high GV, 15% of time in hypoglycemia and hyperglycemic spikes. After prescription of a low glycemic index diet, his GV increased and time in hypoglycemia decreased. Through the detailed self-monitoring needed for CGM, we discovered severe anxiety symptoms, consumption of simple carbohydrates and lack of meal structure. He was referred for more intensive psychological counseling. In conclusion, CGM can detect disorders in glucose homeostasis derived both from the mechanisms of bariatric surgery, as well as the patient’s behaviors and mental health, improving decision-making during follow-up. LEARNING POINTS: High glycemic variability is frequent in patients operated with gastric bypass. Diverse eating patterns, such as prolonged fasting and simple carbohydrate ingestion, and mental health disorders, including anxiety, can promote and be confused with worsened hypoglycemia. CGM requires a detailed record of food ingested that can be accompanied by associated factors (circumstances, eating patterns, emotional symptoms). This allows the detection of particular behaviors and amount of dietary simple carbohydrates to guide recommendations provided within clinical care of these patients.