title: High glycemic variability assessed by continuous glucose monitoring after surgical treatment of obesity by gastric bypass.
abstract: BACKGROUND
  Obesity surgery elicits complex changes in glucose metabolism that are difficult to observe with discontinuous glucose measurements. We aimed to evaluate glucose variability after gastric bypass by continuous glucose monitoring (CGM) in a real-life setting.
  
  
  METHODS
  CGM was performed for 4.2 ± 1.3 days in three groups of 10 subjects each: patients who had undergone gastric bypass and who were referred for postprandial symptoms compatible with mild hypoglycemia, nonoperated diabetes controls, and healthy controls.
  
  
  RESULTS
  The maximum interstitial glucose (IG), SD of IG values, and mean amplitude of glucose excursions (MAGE) were significantly higher in operated patients and in diabetes controls than in healthy controls. The time to the postprandial peak IG was significantly shorter in operated patients (42.8 ± 6.0 min) than in diabetes controls (82.2 ± 11.1 min, P = 0.0002), as were the rates of glucose increase to the peak (2.4 ± 1.6 vs. 1.2 ± 0.3 mg/mL/min; P = 0.041). True hypoglycemia (glucose <60 mg/dL) was rare: the symptoms were probably more related to the speed of IG decrease than to the glucose level achieved. Half of the operated patients, mostly those with a diabetes background before surgery, had postprandial glucose concentrations above 200 mg/dL (maximum IG, 306 ± 59 mg/dL), in contrast to the normal glucose concentrations in the fasting state and 2 h postmeal.
  
  
  CONCLUSIONS
  Glucose variability is exaggerated after gastric bypass, combining unusually high and early hyperglycemic peaks and rapid IG decreases. This might account for postprandial symptoms mimicking hypoglycemia but often seen without true hypoglycemia. Early postprandial hyperglycemia might be underestimated if glucose measurements are done 2 h postmeal.
authors.affiliation: Cardiovascular and Metabolic Department, University Hospital Center of Toulouse, University of Toulouse, Toulouse, France.
authors.forename: Helene
authors.initials: H
authors.lastname: Hanaire
authors.forename: Monelle
authors.initials: M
authors.lastname: Bertrand
authors.forename: Bruno
authors.initials: B
authors.lastname: Guerci
authors.forename: Yves
authors.initials: Y
authors.lastname: Anduze
authors.forename: Eric
authors.initials: E
authors.lastname: Guillaume
authors.forename: Patrick
authors.initials: P
authors.lastname: Ritz
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism; D045604:Extracellular Fluid / Q000378:metabolism; D005260:Female; D005602:France / Q000453:epidemiology; D015390:Gastric Bypass / Q000009:adverse effects*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000175:diagnosis*; D007003:Hypoglycemia / Q000175:diagnosis*; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D009765:Obesity / Q000378:metabolism* / Q000601:surgery; D011183:Postoperative Complications / Q000175:diagnosis*; D019518:Postprandial Period; D015203:Reproducibility of Results
chemical_list: D005947:Glucose