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. 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 z 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 z kg-1 BM; 660±21 kcal) and administered a Full, 75%, or 50% rapidacting insulin dose. Blood glucose concentrations were measured for 3 h postmeal. Interstitial glucose was recorded for 20 h after leaving the laboratory using a continuou s 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 z 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 freeliving 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. © 2013 by the American Diabetes Association.