Insulin + Insulinoma

Question 1

Where is pro-insulin formed?

Answer 1

Rough endoplasmic reticulum in pancreatic beta cells

Question 2

What is pro-insulin cleaved to form?

Answer 2

Insulin and C-peptide

Question 3

What triggers the release of insulin from secretory granules?

Answer 3

Ca2+

Question 4

What is the primary stimulus for insulin secretion?

Answer 4

Hyperglycaemia

Question 5

List the functions of insulin

Answer 5

• Glucose utilisation and glycogen synthesis
• Inhibits lipolysis
• Reduces muscle protein loss
• Increases cellular uptake of potassium (via stimulation of Na+/K+ ATPase pump)

Question 6

How do rapid-acting human insulin analogues compare to soluble insulin?

Answer 6

Act faster and have a shorter duration of action

Question 7

What is the purpose of rapid/short-acting ‘bolus’ insulin in ‘basal-bolus’ regimes?

Answer 7

Administered before meals

Question 8

Provide examples of rapid-acting insulin

Answer 8

• Insulin aspart: NovoRapid
• Insulin lispro: Humalog

Question 9

What are examples of short-acting insulins?

Answer 9

• Actrapid (human, pyr)
• Humulin S (human, prb)

Question 10

What type of insulin is isophane insulin?

Answer 10

Intermediate-acting insulin

Question 11

List examples of long-acting insulins

Answer 11

• Insulin determir (Levemir)
• Insulin glargine (Lantus)

Question 12

What is important to prevent when administering insulin subcutaneously?

Answer 12

Lipodystrophy

Question 13

What are insulin pumps used for?

Answer 13

Deliver continuous basal infusion and patient-activated bolus dose

Question 14

When is intravenous insulin used?

Answer 14

For patients who are acutely unwell, e.g., diabetic ketoacidosis

Question 15

What are common side effects of insulin?

Answer 15

Hypoglycaemia

Question 16

What should patients be taught regarding hypoglycaemia?

Answer 16

Signs include sweating, anxiety, blurred vision, confusion, aggression

Question 17

What should conscious patients do during a hypoglycaemic episode?

Answer 17

Take 10-20g of a short-acting carbohydrate

Question 18

What is lipodystrophy?

Answer 18

Atrophy/lumps of subcutaneous fat

Question 19

What is an insulinoma?

Answer 19

A neuroendocrine tumour deriving mainly from pancreatic Islets of Langerhans cells

Question 20

What is the most common pancreatic endocrine tumour?

Answer 20

Insulinoma

Question 21

What percentage of insulinomas are malignant?

Answer 21

10%

Question 22

What are symptoms of hypoglycaemia associated with insulinoma?

Answer 22

Typically early in morning or just before meal, e.g., diplopia, weakness

Question 23

How is insulinoma diagnosed?

Answer 23

Supervised, prolonged fasting (up to 72 hours) and CT pancreas

Question 24

What is the management for insulinoma?

Answer 24

Surgery, diazoxide, and somatostatin if surgery is not an option

Question 25

What do meglitinides do?

Answer 25

Increase pancreatic insulin secretion

Question 26

What is a characteristic of patients with MODY?

Answer 26

Mild non-ketotic hyperglycemia detected incidentally

Question 27

How do patients with MODY2 typically present?

Answer 27

Mild, stable fasting hyperglycemia

Question 28

What should be suspected in individuals with persistent, asymptomatic hyperglycemia before age 25?

Answer 28

MODY

Question 29

What is the typical treatment for MODY2?

Answer 29

Often does not require specific treatment

Question 30

What type of medication do patients with MODY associated with HNF1A respond well to?

Answer 30

Low-dose sulfonylureas

Question 31

What may be necessary for some MODY patients during pregnancy?

Answer 31

Insulin therapy