A 55-year-old man presents to the emergency department with confusion, sweating, and palpitations. He was diagnosed with type 2 diabetes mellitus 5 years ago and is on a regimen of metformin and glimepiride. His wife mentioned he skipped dinner after taking his usual medications. On examination, he appears diaphoretic and lethargic.

Lab findings include:

• Blood glucose: 40 mg/dL

• Plasma insulin level: High

• C-peptide level: High

Which of the following is the most likely cause of this patient’s symptoms?

• A) Insulinoma

• B) Exogenous insulin administration

• C) Sulfonylurea-induced hypoglycemia

• D) Reactive hypoglycemia

• E) Addison's disease

Correct Answer: C) Sulfonylurea-induced hypoglycemia

55-year-old man with confusion, sweating, palpitations, and history of type 2 diabetes mellitus.

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Medication:
On Metformin and Glimepiride.

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Skipped Dinner:
Did not consume carbohydrates after taking medications.

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Glimepiride Action:
Stimulates insulin secretion from the pancreas.

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Insulin Levels:
Insulin ↑ (excess production due to glimepiride).

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Blood Glucose Availability:
Glucose availability ↓ (due to missed meal).

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Resulting Blood Glucose Level:
Blood glucose: 40 mg/dL (hypoglycemia).

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Plasma Insulin Level:
Plasma insulin: High (indicates endogenous production).

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C-Peptide Level:
C-peptide: High (further confirms endogenous insulin secretion)

Inadequate Glucose Availability:
Brain and peripheral tissues receive insufficient glucose.

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Neuronal Dysfunction:
Brain relies primarily on glucose for energy.
🧠 Key Insight: Neurons are very sensitive to low glucose.

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Initial Symptoms:

• Cognitive Dysfunction: Confusion, difficulty concentrating, irritability.
  🧠 Insight: Resulting from inadequate energy for neuronal activity.

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Activation of Autonomic Nervous System:
Low blood glucose triggers compensatory mechanisms.

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Release of Catecholamines:
Epinephrine and norepinephrine are secreted.
🧠 Key Insight: Body's attempt to restore blood glucose.

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Catecholamines Effects:

• Increased Heart Rate: Palpitations occur due to adrenergic stimulation.

• Tremors: Increased muscle activity results from adrenaline.

• Sweating: Activation of sweat glands due to stress response.

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Neuroglycopenic Symptoms:
As glucose levels drop further, the brain suffers:

• Severe Cognitive Effects: Confusion, disorientation, seizures, potential loss of consciousness.
  🧠 Key Insight: Direct consequence of glucose deprivation in the brain.

Explanation of Options

A) Insulinoma:
Endogenous hyperinsulinemia due to tumor → No tumor found, unlikely.

B) Exogenous Insulin Administration:
High insulin from an external source → Patient is not on insulin therapy, unlikely.

C) Sulfonylurea-induced Hypoglycemia:
Excess insulin from glimepiride with missed meal → Correct answer, leading to hypoglycemia.

D) Reactive Hypoglycemia:
Hypoglycemia occurs after meals due to rapid insulin release → No history of postprandial symptoms, unlikely.

E) Addison's Disease:
Adrenal insufficiency leading to low cortisol → Symptoms do not align with adrenal crisis, unlikely.

Flashcards

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