title: Large pre- and postexercise rapid-acting insulin reductions preserve glycemia and prevent early- but not late-onset hypoglycemia in patients with type 1 diabetes.
abstract: OBJECTIVE
  To examine the acute and 24-h glycemic responses to reductions in postexercise rapid-acting insulin dose in type 1 diabetic patients.
  
  
  METHODS
  After preliminary testing, 11 male patients (24 ± 2 years, HbA1c 7.7 ± 0.3%; 61 ± 3.4 mmol/mol) attended the laboratory on three mornings. Patients consumed a standardized breakfast (1 g carbohydrate · kg(-1) BM; 380 ± 10 kcal) and self-administered a 25% rapid-acting insulin dose 60 min prior to performing 45 min of treadmill running at 72.5 ± 0.9% VO2peak. At 60 min postexercise, patients ingested a meal (1 g carbohydrate · kg(-1) BM; 660 ± 21 kcal) and administered a Full, 75%, or 50% rapid-acting insulin dose. Blood glucose concentrations were measured for 3 h postmeal. Interstitial glucose was recorded for 20 h after leaving the laboratory using a continuous glucose monitoring system.
  
  
  RESULTS
  All glycemic responses were similar across conditions up to 60 min postexercise. After the postexercise meal, blood glucose was preserved under 50%, but declined under Full and 75%. Thence at 3 h, blood glucose was highest under 50% (50% [10.4 ± 1.2] vs. Full [6.2 ± 0.7] and 75% [7.6 ± 1.2 mmol · L(-1)], P = 0.029); throughout this period, all patients were protected against hypoglycemia under 50% (blood glucose ≤ 3.9; Full, n = 5; 75%, n = 2; 50%, n = 0). Fifty percent continued to protect patients against hypoglycemia for a further 4 h under free-living conditions. However, late-evening and nocturnal glycemia were similar; as a consequence, late-onset hypoglycemia was experienced under all conditions.
  
  
  CONCLUSIONS
  A 25% pre-exercise and 50% postexercise rapid-acting insulin dose preserves glycemia and protects patients against early-onset hypoglycemia (≤ 8 h). However, this strategy does not protect against late-onset postexercise hypoglycemia.
authors.affiliation: Corresponding author: Daniel J. West, d.j.west@northumbria.ac.uk.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Campbell
authors.forename: Mark
authors.initials: M
authors.lastname: Walker
authors.forename: Michael I
authors.initials: MI
authors.lastname: Trenell
authors.forename: Djordje G
authors.initials: DG
authors.lastname: Jakovljevic
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Stevenson
authors.forename: Richard M
authors.initials: RM
authors.lastname: Bracken
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Bain
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: West
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000502:physiology*; D018592:Cross-Over Studies; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007003:Hypoglycemia / Q000517:prevention & control*; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007328:Insulin / Q000097:blood; D061266:Insulin, Short-Acting / Q000008:administration & dosage*; D008297:Male; D012890:Sleep / Q000502:physiology
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D061266:Insulin, Short-Acting