Question

A 10-year-old boy presents to the emergency department with fatigue, frequent urination, and excessive thirst for the past week. He has also experienced unintended weight loss. Physical examination reveals dry mucous membranes and tachycardia. His lab results are as follows:

• Blood glucose: 350 mg/dL (normal fasting: <100 mg/dL)

• Serum bicarbonate: 15 mEq/L (normal: 22–29 mEq/L)

• Arterial pH: 7.28 (normal: 7.35–7.45)

• Serum ketones: Positive

Which of the following is the underlying mechanism of his condition?

A) Increased insulin production
B) Autoimmune destruction of pancreatic beta cells
C) Increased hepatic gluconeogenesis due to insulin resistance
D) Defective insulin receptors on muscle and fat cells
E) Decreased glucagon secretion

Correct Answer: B) Autoimmune destruction of pancreatic beta cells

Genetic Predisposition
⬇️
Environmental Triggers (e.g., viral infections, dietary factors)

⬇️

Initiate autoimmune response

⬇️

Autoimmune Response Against Pancreatic Beta Cells
⮕ Destruction of Beta Cells due to T-cells & autoantibodies 🧠

⬇️

 ↓ Insulin Production
Beta cells fail to secrete adequate insulin

⬇️

🧠 Lack of Insulin’s Role in Glucose Uptake
↓ Cellular glucose absorption in muscle & fat

⬇️

 ↑ Blood Glucose Levels (Hyperglycemia)
Liver continues gluconeogenesis unregulated by insulin

⬇️

Body Triggers Compensatory Responses
↓ Cellular glucose access ⮕ Body uses alternative energy sources

⬇️

⬆️ ↑ Lipolysis and Protein Catabolism
Fat breakdown for energy ⮕ Free Fatty Acids ↑

⬇️

🧠 ↑ Free Fatty Acids Converted to Ketones in the Liver
Leads to Ketosis and Metabolic Acidosis (↓ Bicarbonate, ↓ pH)

⬇️

Clinical Signs of Diabetic Ketoacidosis (DKA):

• Polyuria: Osmotic diuresis from high glucose ⮕ water drawn out

• Polydipsia: Dehydration due to fluid loss triggers thirst

• Weight Loss: Breakdown of fat & muscle for energy

Explanations for Incorrect Options

• Increased Insulin Production ⮕ Incorrect because beta cells are destroyed, preventing insulin secretion.

• Increased Gluconeogenesis due to Insulin Resistance ⮕ Seen in T2DM (insulin resistance), not T1DM, which lacks insulin production.

• Defective Insulin Receptors on Muscle/Fat Cells ⮕ Typical of T2DM where cells resist insulin; T1DM lacks insulin itself.

• Decreased Glucagon Secretion ⮕ Unlikely in T1DM; glucagon often increases, worsening hyperglycemia and ketosis.

Flashcards

Stay Hungry, Stay Curious!

Your Brother In This Struggle!

Dr. Shoaib Ahmad