BC ADM Fundamentals & Core Concepts 5 — Questions and Answers
Question 1: Acanthosis nigricans in a patient with diabetes is a clinical marker of:
- Autoimmune beta-cell destruction
- Severe insulin resistance with hyperinsulinemia (Correct answer)
- Diabetic nephropathy stage 3
- Hypoglycemia unawareness
Correct answer: Severe insulin resistance with hyperinsulinemia
Acanthosis nigricans (velvety hyperpigmentation in skin folds) is a cutaneous sign of significant insulin resistance and chronic hyperinsulinemia.
Question 2: The 'glucose toxicity' concept in type 2 diabetes refers to:
- Direct nephrotoxic effects of glucose on proximal tubular cells
- Reversible impairment of beta-cell function and insulin sensitivity caused by chronic hyperglycemia (Correct answer)
- Irreversible structural damage to glomeruli from sustained hyperglycemia
- Glucosuria-induced dehydration leading to prerenal azotemia
Correct answer: Reversible impairment of beta-cell function and insulin sensitivity caused by chronic hyperglycemia
Glucose toxicity describes how chronic hyperglycemia itself reversibly impairs both beta-cell insulin secretion and peripheral insulin sensitivity, perpetuating the hyperglycemia.
Question 3: Which statement about the HbA1c test limitation is most clinically relevant for an advanced diabetes manager?
- HbA1c cannot be used in patients over age 65
- HbA1c may be falsely low in conditions that shorten red blood cell lifespan, such as hemolytic anemia (Correct answer)
- HbA1c overestimates average glucose in African American patients
- HbA1c is unreliable in any patient using insulin therapy
Correct answer: HbA1c may be falsely low in conditions that shorten red blood cell lifespan, such as hemolytic anemia
Conditions that shorten RBC lifespan (hemolytic anemia, hemoglobinopathies, recent transfusion) cause falsely low HbA1c by reducing red cell exposure time to glucose.
Question 4: Insulin secretion occurs in a biphasic pattern. The first phase primarily reflects:
- New insulin synthesis triggered by elevated glucose
- Release of pre-formed insulin granules docked at the beta-cell membrane (Correct answer)
- GLP-1–mediated potentiation of the adenylyl cyclase pathway
- Parasympathetic stimulation via the vagus nerve
Correct answer: Release of pre-formed insulin granules docked at the beta-cell membrane
The first-phase insulin spike (within 1–3 minutes of glucose rise) represents exocytosis of a readily releasable pool of pre-docked secretory granules.
Question 5: Latent autoimmune diabetes in adults (LADA) is distinguished from type 2 diabetes by:
- Older age at diagnosis and higher BMI
- Presence of islet autoantibodies (typically GAD65) and progressive beta-cell loss (Correct answer)
- Requirement for oral agents rather than insulin
- Absence of any family history of diabetes
Correct answer: Presence of islet autoantibodies (typically GAD65) and progressive beta-cell loss
LADA presents clinically like type 2 but is distinguished by islet autoantibodies (most commonly anti-GAD65) and inevitable progression to insulin dependence.
Question 6: Which mechanism explains why patients with long-standing type 1 diabetes may lose hypoglycemia awareness?
- Progressive renal failure alters glucose clearance kinetics
- Repeated hypoglycemia blunts sympathoadrenal responses and shifts glycemic thresholds for symptoms (Correct answer)
- Peripheral neuropathy destroys glucose-sensing neurons in muscle
- Chronic insulin use downregulates hepatic glucagon receptors
Correct answer: Repeated hypoglycemia blunts sympathoadrenal responses and shifts glycemic thresholds for symptoms
Hypoglycemia-associated autonomic failure (HAAF) results from repeated hypoglycemia that reduces epinephrine and symptom responses, raising the threshold at which symptoms appear.
Question 7: According to the pathophysiological 'ominous octet' described by DeFronzo, which of the following is NOT one of the eight defects contributing to type 2 diabetes hyperglycemia?
- Increased hepatic glucose production
- Decreased incretin effect
- Increased lipolysis in adipocytes
- Reduced erythropoietin production by the kidney (Correct answer)
Correct answer: Reduced erythropoietin production by the kidney
DeFronzo's ominous octet includes defects in beta cells, alpha cells, muscle, liver, adipocytes, brain, kidney (glucose reabsorption), and gut (incretins) — erythropoietin is not part of it.
BC ADM Fundamentals & Core Concepts 5
Acanthosis nigricans in a patient with diabetes is a clinical marker of: