TABLE 1

Physiologic responses to decreasing plasma glucose concentrations

ResponseGlycemic threshold (mg/dl [mmol/l])*Physiologic effectsRole in prevention or correction of hypoglycemia (glucose counterregulation)
↓ Insulin80–85 [4.4–4.7]Ra (↓Rd)Primary glucose regulatory factor, first defense against hypoglycemia
↑ Glucagon65–70 [3.6–3.9]RaPrimary glucose counterregulatory factor, second defense against hypoglycemia
↑ Epinephrine65–70 [3.6–3.9]Ra, ↓RdInvolved, critical when glucagon is deficient, third defense against hypoglycemia
↑ Cortisol and growth hormone65–70 [3.6–3.9]Ra, ↓RdInvolved, not critical
Symptoms50–55 [2.8–3.1]↑Exogenous glucosePrompt behavioral defense (food ingestion)
↓ Cognition<50 [<2.8](Compromises behavioral defense)
  • * Arterialized venous, not venous, plasma glucose concentrations.

  • Ra, rate of glucose appearance, glucose production by the liver and kidneys; Rd, rate of glucose disappearance, glucose utilization by insulin-sensitive tissues such as skeletal muscle (no direct effect on central nervous system glucose utilization). This table was prepared initially for Cryer PE: Glucose homeostasis and hypoglycemia. In Williams Textbook of Endocrinology, 11th Edition. Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, Eds. Saunders, Philadelphia, 2008, p. 1503–1533.