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

Abstract

. Acute, sameday effects of antecedent exercise on counterregulatory responses to subsequent hypoglycemia in type 1 diabetes mellitus. Am J Physiol Endocrinol Metab 290: E1331-E1338, 2006. First published January 31, 2006 doi:10.1152/ajpendo.00283.2005.-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 Ϯ 4 pmol/l) hypoglycemic (2.8 Ϯ 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% V O2 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 (Rd) 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 Rd was reduced during afternoon hypoglycemia following morning hypoglycemia, indicating posthypoglycemic insulin resistance. After morning exercise, endogenous glucose production was blunted, but glucose Rd 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 ANTECEDENT EPISODES OF HYPOGLYCEMIA occurring 24 h before exercise have been found to blunt autonomic counterregulatory responses to subsequent prolonged moderate-intensity exercise (90 min at 50% V O 2 max ) by ϳ50% in both nondiabetic (8) and type 1 diabetes mellitus (T1DM) (19) individuals. In fact, it seems that this relationship is reciprocal; that is, recent antecedent episodes of prolonged moderate-intensity exercise have also been found to blunt autonomic counterregulatory responses during subsequent hypoglycemia occurring 24 h later in healthy (17, 30) and T1DM subjects (33). However, clinically, exercise-induced hypoglycemia has been reported to occur within 2 h after exercise.Although acute exercise-induced hypoglycemia in T1DM may at least partially stem from iatrogenic causes (i.e., in balance of subcutaneous insulin and metabolic needs), we (13) have demonstrated that morning hypoglycemia could acutely reduce neuroendocrine and symptom responses to subsequent, same-day, afternoon hypoglycemia in nondiabetic individuals. Des...

Effects of a Selective Serotonin Reuptake Inhibitor, Fluoxetine, on Counterregulatory Responses to Hypoglycemia in Healthy Individuals

“…DagogoJack et al (32) demonstrated that hypoglycemic symptoms can increase before adrenomedullary or sympathetic neural responses in patients with hypoglycemia-associated autonomic failure (32). Sandoval et al (33) and Davis et al (17) also demonstrated that hypoglycemic symptoms are preserved relative to blunting of other ANS responses following antecedent stress. Thus, previous studies seem to indicate that hypoglycemic symptoms are resultant of central ANS drive and are preserved high in the hierarchy of ANS responses to hypoglycemia.…”

“…The origin of hypoglycemic symptoms during hypoglycemia is complex. Previous studies demonstrated scenarios whereby discordant responses between autonomic symptoms and catecholamine responses can exist during hypoglycemia (17,(31)(32)(33). Generally, studies have determined that autonomic symptoms can be preserved despite reduced activity in other branches of the sympathetic nervous system.…”

Effects of Performing Morning Versus Afternoon Exercise on Glycemic Control and Hypoglycemia Frequency in Type 1 Diabetes Patients on Sensor-Augmented Insulin Pump Therapy

“…Its lower concentrations in the afternoon and particularly at midnight may favor hypoglycemia by reducing gluconeogenesis and responses to glucagon. 7,8 Further research is needed to better quantify this phenomenon. Other possible explanation could be the absence of insulin boluses before the morning exercise since these was performed in a fasting state, however, we aimed to reduce this difference as the afternoon exercise session was conducted 4 hours after lunch, which is considered enough time to minimize the effect of the fast-acting insulin used for that meal.…”

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