Diabetes Education Certification Diabetes Pathophysiology & Types 2 — Questions and Answers
Question 1: Which autoantibody is MOST specific for identifying autoimmune Type 1 diabetes in adults?
- Anti-insulin antibody (IAA)
- Glutamic acid decarboxylase antibody (GADA) (Correct answer)
- Islet cell antibody (ICA)
- Zinc transporter 8 antibody (ZnT8A)
Correct answer: Glutamic acid decarboxylase antibody (GADA)
GADA (anti-GAD65) is the most sensitive and specific autoantibody for autoimmune Type 1 diabetes in adults and persists longest after diagnosis.
Question 2: In Type 2 diabetes, which pathophysiological defect is typically present BEFORE fasting hyperglycemia develops?
- Impaired fasting glucose
- Loss of first-phase insulin secretion (Correct answer)
- Glucagon suppression failure
- Decreased hepatic glucose uptake
Correct answer: Loss of first-phase insulin secretion
Loss of first-phase (rapid) insulin secretion in response to glucose is an early defect in Type 2 diabetes that precedes overt fasting hyperglycemia.
Question 3: Latent Autoimmune Diabetes in Adults (LADA) is BEST distinguished from Type 2 diabetes by:
- Age of onset over 30 years
- Presence of pancreatic autoantibodies (Correct answer)
- Initial response to oral agents
- Body mass index under 25
Correct answer: Presence of pancreatic autoantibodies
The presence of pancreatic autoantibodies (most commonly GADA) is the defining feature that distinguishes LADA from Type 2 diabetes.
Question 4: Maturity-Onset Diabetes of the Young (MODY) is primarily caused by:
- Autoimmune destruction of beta cells
- Severe insulin resistance in peripheral tissues
- Single-gene mutations affecting beta cell function (Correct answer)
- Mitochondrial DNA mutations
Correct answer: Single-gene mutations affecting beta cell function
MODY is caused by single-gene (monogenic) mutations that impair beta cell function, distinguishing it from the polygenic Type 1 and Type 2 diabetes.
Question 5: In Type 1 diabetes, which immune cells are primarily responsible for beta cell destruction in the pancreatic islets?
- B lymphocytes
- CD4+ T helper cells
- CD8+ cytotoxic T lymphocytes (Correct answer)
- Natural killer cells
Correct answer: CD8+ cytotoxic T lymphocytes
CD8+ cytotoxic T lymphocytes are the primary effector cells that directly kill insulin-producing beta cells in Type 1 diabetes.
Question 6: A patient with Type 2 diabetes has progressive beta cell failure. Which mechanism BEST explains this deterioration?
- Ongoing autoimmune attack
- Glucotoxicity and lipotoxicity causing beta cell apoptosis (Correct answer)
- Amyloid deposition replacing exocrine tissue
- Mitochondrial gene mutations
Correct answer: Glucotoxicity and lipotoxicity causing beta cell apoptosis
Chronic exposure to elevated glucose (glucotoxicity) and free fatty acids (lipotoxicity) promotes beta cell oxidative stress and apoptosis, driving progressive beta cell failure in Type 2 diabetes.
Question 7: Neonatal diabetes mellitus diagnosed before 6 months of age is MOST likely caused by:
- Transplacental transfer of maternal autoantibodies
- Monogenic mutations affecting ATP-sensitive potassium channels (Correct answer)
- Type 1 autoimmune diabetes
- Congenital rubella infection
Correct answer: Monogenic mutations affecting ATP-sensitive potassium channels
Most permanent neonatal diabetes is caused by monogenic mutations (e.g., KCNJ11 or ABCC8) that impair the ATP-sensitive potassium channels needed for insulin secretion.
Diabetes Education Certification Diabetes Pathophysiology & Types 2
Which autoantibody is MOST specific for identifying autoimmune Type 1 diabetes in adults?