title: Continuous Glucose Monitoring After Gastric Bypass to Evaluate the Glucose Variability After a Low-Carbohydrate Diet and to Determine Hypoglycemia.
abstract: Roux-en-Y gastric bypass (RYGB) alters glucose metabolism and can cause postprandial hypoglycemia. Continuous glucose monitoring (CGM) has been proposed as an evaluation tool in hypoglycemic RYGB individuals. The objective of this study is to investigate the use of CGM in clinical decision-making including diagnosing hypoglycemia and evaluating treatment effects. Furthermore, we aim to assess its accuracy in RYGB-operated individuals.
  
  
  
  Thirteen RYGB individuals with symptomatic hypoglycemia and 13 asymptomatic RYGB individuals underwent CGM for 5 days. During this period, a mixed-meal test with concomitant plasma glucose (PG) measurements was performed. Furthermore, the RYGB individuals followed a low-carbohydrate diet (LCD) for 1 day and maintained their ordinary diet (OD) for the rest of the period.
  
  
  
  LCD reduced the CGM-determined glycemic variability of the mean interstitial fluid glucose (IFG) significantly compared to OD (p < 0.0001). Receiver operating characteristic analysis confirmed that low blood glucose index (e.g., the frequency and amplitude of hypoglycemic events) is the most reliable parameter related to the development of symptomatic hypoglycemia, with a sensitivity of 0.91 (confidence interval [CI] 0.59; 1.00) and a specificity of 0.77 (CI 0.46; 0.95). However, CGM, measuring the IFG in the subcutaneous adipose tissue, overestimated the minimum glucose levels by 1.1 ± 0.9 mmol/l compared with PG.
  
  
  
  CGM was a good method for demonstrating increased glycemic variability among RYGB individuals and for displaying dietary effects on reducing this glycemic variability, including hypoglycemic events. In RYGB individuals, CGM-measured IFG overestimated the real glucose value by about 1 mmol/l in the hypoglycemic range. This should be taken into consideration if CGM is used to diagnose hypoglycemia after RYGB.
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, 2nd Floor, Building 3C, Tage-Hansens Gade 2, Aarhus C, 8000, Aarhus, Denmark. joanni@rm.dk.
authors.forename: Joan Bach
authors.initials: JB
authors.lastname: Nielsen
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, 2nd Floor, Building 3C, Tage-Hansens Gade 2, Aarhus C, 8000, Aarhus, Denmark.
authors.forename: Caroline Bruun
authors.initials: CB
authors.lastname: Abild
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, 2nd Floor, Building 3C, Tage-Hansens Gade 2, Aarhus C, 8000, Aarhus, Denmark.
authors.forename: Ane Mathilde
authors.initials: AM
authors.lastname: Pedersen
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, 2nd Floor, Building 3C, Tage-Hansens Gade 2, Aarhus C, 8000, Aarhus, Denmark.
authors.forename: Steen Bønløkke
authors.initials: SB
authors.lastname: Pedersen
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, 2nd Floor, Building 3C, Tage-Hansens Gade 2, Aarhus C, 8000, Aarhus, Denmark.
authors.forename: Bjørn
authors.initials: B
authors.lastname: Richelsen
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D016022:Case-Control Studies; D050528:Diet, Carbohydrate-Restricted; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D007003:Hypoglycemia / Q000097:blood / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009767:Obesity, Morbid / Q000601:surgery*; D011183:Postoperative Complications / Q000097:blood / Q000517:prevention & control; D012680:Sensitivity and Specificity
chemical_list: D001786:Blood Glucose
keywords: Continuous glucose monitoring; Glucose variability; Hypoglycemia measurement; Low-carbohydrate diet; Method comparison; Roux-en-Y gastric bypass