title: Impact of pre-exercise rapid-acting insulin reductions on ketogenesis following running in Type 1 diabetes.
abstract: OBJECTIVE
  This study examined the effects of reductions to pre-exercise rapid-acting insulin dose on changes in blood beta-hydroxybutyrate, glucose, acid-base balance and counter-regulatory hormone responses to prolonged running in individuals with Type 1 diabetes.
  
  
  METHODS
  Following ethical approval, seven participants with Type 1 diabetes (34±2 years, BMI 27±1 kg/m(2) ) completed this study. After preliminary testing, participants attended the laboratory four times, each time consuming a 1.12 MJ meal (60 g carbohydrate, 2 g fat, 2 g protein), with randomized amounts of their rapid-acting insulin: Full dose (mean 7.3±0.2 units), 75% dose (mean 5.4±0.1 units), 50% dose (mean 3.7±0.1 units) or 25% dose (mean 1.8±0.1 units). After 2-h rest, participants completed 45 min running at 70±1% peak rate of oxygen consumption (VO(2peak) ). Blood metabolites and hormones were recorded over the 2-h rest and 3-h recovery. Data were analysed using repeated-measures ANOVA.
  
  
  RESULTS
  Serum insulin peaked at 60 min in all conditions and was lowest after 25% insulin dose compared with full dose (P=0.03). After the 25% insulin dose immediately pre-exercise glucose concentration was higher than after the full or 50% dose (P<0.05). Resting beta-hydroxybutyrate gradually decreased during 2-h rest (P<0.05) with a similar post-exercise peak of beta-hydroxybutyrate at 3 h (P>0.05). Post-exercise blood pH increased for 5 min to a similar extent with all insulin doses , but the rise with the 25% dose was less compared with the full dose (P=0.01). Blood lactate and plasma catecholamines increased after running similarly with all insulin reduction conditions (P<0.05). Blood glucose area under the curve (BG(auc) ) after the 25% insulin dose was greater than after the 75% dose (P=0.02).
  
  
  CONCLUSIONS
  Ketogenesis following running was not influenced by reductions in pre-exercise rapid-acting insulin dose. This important preparatory strategy aids preservation of blood glucose but poses no greater risk to exercise-induced ketone body formation.
authors.affiliation: Sports and Exercise Science Research Centre, School of Engineering, Swansea University, Singleton Park, Swansea, UK. r.m.bracken@swansea.ac.uk
authors.forename: R M
authors.initials: RM
authors.lastname: Bracken
authors.forename: D J
authors.initials: DJ
authors.lastname: West
authors.forename: J W
authors.initials: JW
authors.lastname: Stephens
authors.forename: L P
authors.initials: LP
authors.lastname: Kilduff
authors.forename: S
authors.initials: S
authors.lastname: Luzio
authors.forename: S C
authors.initials: SC
authors.lastname: Bain
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000328:Adult; D001786:Blood Glucose / Q000187:drug effects* / Q000502:physiology; D015992:Body Mass Index; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D004734:Energy Metabolism / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006801:Humans; D007328:Insulin / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007657:Ketone Bodies / Q000096:biosynthesis*; D010101:Oxygen Consumption / Q000187:drug effects* / Q000502:physiology; D012420:Running / Q000502:physiology*; D016896:Treatment Outcome
chemical_list: D001786:Blood Glucose; D007328:Insulin; D007657:Ketone Bodies; D020155:3-Hydroxybutyric Acid