MCQs on Diabetes – AMC Wise

Written by Dr. James Whitfield (MBBS, FRACGP) – General Practitioner

Question 1

Ethan, a 14-year-old boy, presents with polyuria, polydipsia, and weight loss over the past month. On examination, he appears thin and mildly dehydrated. Laboratory tests reveal a fasting blood glucose of 16 mmol/L and positive islet cell antibodies. His C-peptide level is low.

Which of the following best describes the pathophysiology of his condition?

A) Autoimmune destruction of pancreatic beta cells leading to insulin deficiency
B) Insulin resistance due to obesity and metabolic syndrome
C) Excessive hepatic glucose production with normal insulin secretion
D) Genetic mutation causing defective insulin receptor function
E) Increased insulin secretion due to pancreatic beta cell hyperplasia

Correct Answer: A) Autoimmune destruction of pancreatic beta cells leading to insulin deficiency

Explanation:
Ethan’s presentation with polyuria, polydipsia, weight loss, and laboratory findings of high blood glucose, positive islet cell antibodies, and low C-peptide are characteristic of type 1 diabetes mellitus (T1DM). The fundamental pathophysiology in T1DM is an autoimmune-mediated destruction of pancreatic beta cells, resulting in absolute insulin deficiency. The low C-peptide confirms diminished endogenous insulin production, distinguishing T1DM from type 2 diabetes, where insulin levels may be normal or elevated.

This insulin deficiency leads to impaired glucose uptake by peripheral tissues and increased hepatic glucose output, causing hyperglycemia. Without insulin, fat breakdown increases, which can lead to ketoacidosis if untreated.

In contrast, type 2 diabetes mellitus primarily involves insulin resistance (option B) with relative insulin deficiency developing later. Genetic insulin receptor defects (option D) are rare causes of severe insulin resistance and are not typical for T1DM. Increased insulin secretion (option E) does not occur in T1DM but can be seen in early stages of type 2 diabetes.

Question 2

Daniel, a 52-year-old man with a BMI of 31 kg/m², presents for a routine check-up. He reports increased fatigue over the past few months and occasional blurred vision. He has a family history of type 2 diabetes (his father was diagnosed at 60). His blood pressure is 138/84 mmHg. He denies polyuria or polydipsia. A random blood glucose is 9.8 mmol/L, and HbA1c is 7.1%.

Which of the following confirms the diagnosis of type 2 diabetes mellitus in this patient?

A) Fasting plasma glucose ≥7.0 mmol/L
B) HbA1c ≥6.5%
C) Two-hour oral glucose tolerance test (OGTT) ≥11.1 mmol/L
D) Random plasma glucose ≥11.1 mmol/L with classic symptoms
E) Any of the above

Correct Answer: E) Any of the above

Explanation:
Type 2 diabetes mellitus (T2DM) is commonly diagnosed in adults with risk factors such as obesity, family history, sedentary lifestyle, and features of metabolic syndrome. Daniel has several risk factors and an HbA1c of 7.1%, which alone is sufficient to diagnose diabetes.

The diagnostic criteria for diabetes mellitus include any one of the following (confirmed on a second test if asymptomatic):

Fasting plasma glucose (FPG) ≥7.0 mmol/L
HbA1c ≥6.5% (48 mmol/mol)
2-hour plasma glucose ≥11.1 mmol/L during a 75g oral glucose tolerance test (OGTT)
Random plasma glucose ≥11.1 mmol/L in the presence of classic symptoms (e.g., polyuria, polydipsia, weight loss)

Because each of these criteria is sufficient to confirm the diagnosis, the correct answer is E) Any of the above.

In Daniel’s case, despite the absence of overt hyperglycemic symptoms, his HbA1c ≥6.5% meets the diagnostic threshold. The HbA1c reflects the average glucose level over the preceding 2–3 months and is a reliable screening and diagnostic tool, especially in asymptomatic patients.

Question 3

Priya, a 23-year-old woman with type 1 diabetes mellitus, is brought to the Emergency Department by her roommate due to vomiting, abdominal pain, and rapid breathing. She has been feeling unwell for a few days and missed her insulin doses. On examination, she is tachypnoeic with deep laboured breathing and has fruity-smelling breath. Her capillary blood glucose is 22 mmol/L. Venous blood gas shows a pH of 7.1 and bicarbonate of 10 mmol/L. Urinalysis shows ketones 3+ and glucose 3+.

Which of the following is the most appropriate initial management step?

A) Administer sodium bicarbonate
B) Start intravenous dextrose
C) Administer intravenous insulin and fluids
D) Give subcutaneous long-acting insulin
E) Immediate intubation and mechanical ventilation

Correct Answer: C) Administer intravenous insulin and fluids

Explanation:
Priya is presenting with diabetic ketoacidosis (DKA) — a potentially life-threatening complication of type 1 diabetes due to absolute insulin deficiency. It is characterised by:

Hyperglycaemia (usually >11 mmol/L)
Ketonaemia or ketonuria
Metabolic acidosis (pH <7.3, bicarbonate <15 mmol/L)

Management is urgent and requires:

Intravenous fluid resuscitation with isotonic saline to correct dehydration.
Intravenous insulin infusion to stop ketone production and lower blood glucose.
Potassium monitoring and replacement if needed.
Later addition of dextrose once blood glucose drops (to prevent hypoglycaemia while continuing insulin).

Bicarbonate therapy is not routinely recommended unless the pH is <6.9. Intubation is rarely needed unless there’s a decreased level of consciousness. Subcutaneous insulin is not appropriate in moderate/severe DKA.

5. Endocrine Module

5.1 Diabetes

5.2 Thyroid

5.3 Breast

5.4 Adrenals

5.5 Osteoporosis

5.6 Other Endocrine Disorders

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