Large Pre- and Postexercise Rapid-Acting Insulin Reductions Preserves Glycemia and Prevents Early- but Not Late-Onset Hypoglycemia in Patients With Type 1 Diabetes
- Matthew D. Campbell, BSC1,
- Mark Walker, MD2,
- Michael I. Trenell, PHD2,
- Djordje G. Jakovljevic, PHD3,
- Emma J. Stevenson, PHD1,
- Richard M. Bracken, PHD4,
- Stephen C. Bain, MD5 and
- Daniel J. West, PHD1⇑
- 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.
- 2Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, U.K.
- 3Institute for Ageing and Health, Faculty of Medicine, Newcastle University, Newcastle-upon-Tyne, U.K.
- 4Applied Sports, Technology, Exercise, and Medicine Research Centre, College of Engineering, Swansea University, Swansea, U.K.
- 5Diabetes Research Group, College of Medicine, Swansea University, Singleton Park, Swansea, U.K.
- Corresponding author: Daniel J. West, .
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.
- © 2013 by the American Diabetes Association.
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