Effect of prior hyperglycemia on IL-6 responses to exercise in children with type 1 diabetes

General Clinical Research Center and Department of Pediatrics, University of California, Irvine, Orange, California Submitted 14 September 2005 ; accepted in final form 29 November 2005 The proinflammatory cytokine interleukin-6 (IL-6) may modulate the onset and progression of complications of diabetes. As this cytokine increases after exercise, and many other exercise responses are altered by prior glycemic fluctuations, we hypothesized that prior hyperglycemia might exacerbate the IL-6 response to exercise. Twenty children with type 1 diabetes (12 boys/8 girls, age 12–15 yr) performed 29 exercise studies (30-min intermittent cycling at 80% peak O 2 uptake). Children were divided into four groups based on highest morning glycemic reading [blood glucose (BG) < 150, BG 151–200, BG 201–300, or BG > 300 mg/dl]. All exercise studies were performed in the late morning, after hyperglycemia had been corrected and steady-state conditions (plasma glucose 300, 3.2 ± 1.4 ng/ml). Other measured variables (growth hormone, IGF-I, glucagon, epinephrine, cortisol) were not influenced by prior hyperglycemia. Recent prior hyperglycemia markedly influenced baseline and exercise-induced levels of IL-6 in a group of peripubertal children with type 1 diabetes. While exercise is widely encouraged and indeed often considered part of diabetic management, our data underscore the necessity to completely understand all adaptive mechanisms associated with physical activity, particularly in the context of the developing diabetic child. inflammatory cytokines; exercise adaptation; glycemia; insulin Address for reprint requests and other correspondence: P. Galassetti, U.C. Irvine General Clinical Research Center, Bldg. 25, 2 nd Floor, 101 The City Drive, Orange, CA 92868 (e-mail: pgalasse{at}uci.edu )