Large Pre- and Postexercise Rapid-Acting Insulin Reductions Preserves Glycemia and Prevents Early- but Not Late-Onset Hypoglycemia in Patients With Type 1 Diabetes

  1. Daniel J. West, PHD1
  1. 1Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, U.K.
  2. 2Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, U.K.
  3. 3Institute for Ageing and Health, Faculty of Medicine, Newcastle University, Newcastle-upon-Tyne, U.K.
  4. 4Applied Sports, Technology, Exercise, and Medicine Research Centre, College of Engineering, Swansea University, Swansea, U.K.
  5. 5Diabetes Research Group, College of Medicine, Swansea University, Singleton Park, Swansea, U.K.
  1. Corresponding author: Daniel J. West, d.j.west{at}


OBJECTIVE To examine the acute and 24-h glycemic responses to reductions in postexercise rapid-acting insulin dose in type 1 diabetic patients.

RESEARCH DESIGN AND 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.

  • Received November 27, 2012.
  • Accepted January 30, 2013.

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  1. Diabetes Care
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