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This Article Full Text Full Text (PDF) All Versions of this Article: 290/6/E1331    most recent 00283.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Sandoval, D. A. Articles by Davis, S. N. Search for Related Content PubMed PubMed Citation Articles by Sandoval, D. A. Articles by Davis, S. N.

Acute, same-day effects of antecedent exercise on counterregulatory responses to subsequent hypoglycemia in type 1 diabetes mellitus

Departments of ¹Medicine and ²Pediatrics, Vanderbilt University School of Medicine; and ³Nashville Veterans Affairs Medical Center, Nashville, Tennessee

Submitted 23 June 2005 ; accepted in final form 24 January 2006

Exercise-induced hypoglycemia can occur within hours after exercise in type 1 diabetes mellitus (T1DM) patients. This study tested the hypothesis that an acute exercise bout causes (within hours) blunted autonomic and metabolic responses to subsequent hypoglycemia in patients with T1DM. Twelve T1DM patients (3 W/9 M) were studied during a single-step, 2-h hyperinsulinemic (572 ± 4 pmol/l) hypoglycemic (2.8 ± 0.1 mmol/l) clamp 2 h after either a hyperinsulinemic euglycemic (AM EUG) or hypoglycemic clamp (AM HYPO) or after sitting in a chair with basal insulin infusion (AM CON) or 90 min of moderate-intensity exercise (50% O_{2 max}, AM EX). Both AM HYPO and AM EX significantly blunted epinephrine responses and muscle sympathetic nerve activity responses to subsequent hypoglycemia compared with both control groups. Endogenous glucose production was significantly lower and the exogenous glucose infusion rate needed to maintain the hypoglycemic level was significantly greater during subsequent hypoglycemia in AM EX vs. CON. Rate of glucose disposal (R_d) was significantly reduced following AM HYPO. In summary, within 2.5 h, both moderate-intensity AM EX and AM HYPO blunted key autonomic counterregulatory responses. Despite this, glucose R_d was reduced during afternoon hypoglycemia following morning hypoglycemia, indicating posthypoglycemic insulin resistance. After morning exercise, endogenous glucose production was blunted, but glucose R_d was maintained during afternoon hypoglycemia, thereby indicating reduced metabolic defenses against hypoglycemia. These data suggest that exercise-induced counterregulatory failure can occur very rapidly, increasing the risk for hypoglycemia in T1DM within hours.

sympathetic nervous system; hormones