Physiologic responses to decreasing plasma glucose concentrations
| Response . | Glycemic threshold (mg/dl [mmol/l])* . | Physiologic effects . | Role in prevention or correction of hypoglycemia (glucose counterregulation) . |
|---|---|---|---|
| ↓ Insulin | 80–85 [4.4–4.7] | ↑Ra (↓Rd)† | Primary glucose regulatory factor, first defense against hypoglycemia |
| ↑ Glucagon | 65–70 [3.6–3.9] | ↑Ra | Primary glucose counterregulatory factor, second defense against hypoglycemia |
| ↑ Epinephrine | 65–70 [3.6–3.9] | ↑Ra, ↓Rd | Involved, critical when glucagon is deficient, third defense against hypoglycemia |
| ↑ Cortisol and growth hormone | 65–70 [3.6–3.9] | ↑Ra, ↓Rd | Involved, not critical |
| Symptoms | 50–55 [2.8–3.1] | ↑Exogenous glucose | Prompt behavioral defense (food ingestion) |
| ↓ Cognition | <50 [<2.8] | — | (Compromises behavioral defense) |
| Response . | Glycemic threshold (mg/dl [mmol/l])* . | Physiologic effects . | Role in prevention or correction of hypoglycemia (glucose counterregulation) . |
|---|---|---|---|
| ↓ Insulin | 80–85 [4.4–4.7] | ↑Ra (↓Rd)† | Primary glucose regulatory factor, first defense against hypoglycemia |
| ↑ Glucagon | 65–70 [3.6–3.9] | ↑Ra | Primary glucose counterregulatory factor, second defense against hypoglycemia |
| ↑ Epinephrine | 65–70 [3.6–3.9] | ↑Ra, ↓Rd | Involved, critical when glucagon is deficient, third defense against hypoglycemia |
| ↑ Cortisol and growth hormone | 65–70 [3.6–3.9] | ↑Ra, ↓Rd | Involved, not critical |
| Symptoms | 50–55 [2.8–3.1] | ↑Exogenous glucose | Prompt 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.