title: Variability of Insulin Requirements Over 12 Weeks of Closed-Loop Insulin Delivery in Adults With Type 1 Diabetes.
abstract: To quantify variability of insulin requirements during closed-loop insulin delivery.
  
  
  
  We retrospectively analyzed overnight, daytime, and total daily insulin amounts delivered during a multicenter closed-loop trial involving 32 adults with type 1 diabetes. Participants applied hybrid day-and-night closed-loop insulin delivery under free-living home conditions over 12 weeks. The coefficient of variation was adopted to measure variability of insulin requirements in individual subjects.
  
  
  
  Data were analyzed from 1,918 nights, 1,883 daytime periods and 1,564 total days characterized by closed-loop use over 85% of time. Variability of overnight insulin requirements (mean [SD] coefficient of variation 31% [4]) was nearly twice as high as variability of total daily requirements (17% [3], P < 0.001) and was also higher than variability of daytime insulin requirements (22% [4], P < 0.001).
  
  
  
  Overnight insulin requirements were significantly more variable than daytime and total daily amounts. This may explain why some people with type 1 diabetes report frustrating variability in morning glycemia.
authors.affiliation: Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, U.K. Department of Paediatrics, University of Cambridge, Cambridge, U.K.
authors.forename: Yue
authors.initials: Y
authors.lastname: Ruan
authors.affiliation: Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, U.K. Department of Diabetes and Endocrinology, Cambridge University Hospitals National Health Service Foundation Trust, Cambridge, U.K.
authors.forename: Hood
authors.initials: H
authors.lastname: Thabit
authors.affiliation: Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, U.K. Department of Diabetes and Endocrinology, Cambridge University Hospitals National Health Service Foundation Trust, Cambridge, U.K.
authors.forename: Lalantha
authors.initials: L
authors.lastname: Leelarathna
authors.affiliation: Department of Diabetes and Endocrinology, Cambridge University Hospitals National Health Service Foundation Trust, Cambridge, U.K.
authors.forename: Sara
authors.initials: S
authors.lastname: Hartnell
authors.affiliation: Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, U.K. Department of Paediatrics, University of Cambridge, Cambridge, U.K.
authors.forename: Malgorzata E
authors.initials: ME
authors.lastname: Willinska
authors.affiliation: Profil, Neuss, Germany.
authors.forename: Sibylle
authors.initials: S
authors.lastname: Dellweg
authors.affiliation: Profil, Neuss, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Benesch
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Julia K
authors.initials: JK
authors.lastname: Mader
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Manuel
authors.initials: M
authors.lastname: Holzer
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Harald
authors.initials: H
authors.lastname: Kojzar
authors.affiliation: Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, U.K. Department of Diabetes and Endocrinology, Cambridge University Hospitals National Health Service Foundation Trust, Cambridge, U.K.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Evans
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Pieber
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Sabine
authors.initials: S
authors.lastname: Arnolds
authors.affiliation: Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, U.K. Department of Paediatrics, University of Cambridge, Cambridge, U.K. rh347@cam.ac.uk.
authors.forename: Roman
authors.initials: R
authors.lastname: Hovorka
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D018592:Cross-Over Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000009:adverse effects; D007328:Insulin / Q000008:administration & dosage* / Q000009:adverse effects; D007332:Insulin Infusion Systems; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin