Glucose Metabolism

Question 1

How is glucose manufactured?

Answer 1

Gluconeogenesis and glycogenolysis

Question 2

Which organ does not need insulin for glucose uptake?

Answer 2

Brain

Question 3

How can injection of somatostatin treat hypoglycaemia?

Answer 3

• Somatostatin receptors coupled to voltage gated Ca channels in pancreatic B cells
• Somatostatin blocks channel
• Reduces Ca influx and inhibits insulin secretion

Question 4

Which receptors facilitate non-insulin mediated glucose transport?

Answer 4

GLUT 1 and GLUT 3

Question 5

Which receptors mediate glucose uptake in fat and muscle?

Answer 5

GLUT 4

Question 6

What is the mechanism of GLP1 analogues in treating diabetes?

Answer 6

• GLP1 is an incretin

- Stimulates insulin production

Question 7

What might be the consequence of glucokinase mutation?

Answer 7

• Inheritable diabetes

- Glucose not broken down to ATP as easily

Question 8

Which chain of insulin is most active at the receptor?

Answer 8

A chain

Question 9

Insulin is synthesised exclusively in the ____ cells of the _____

Answer 9

Beta cells of pancreas

Question 10

Describe the synthesis and release of insulin.

Answer 10

1. Glucose transported into beta cell by facilitated diffusion via glucose transporter -> inc. [glucose] in beta cell
2. Glucose -> glycolysis -> ATP -> closure of K+ sensitive channels -> depolarisation
3. Influx of Ca -> insulin translocation and exocytosis

Question 11

Why do patients often gain weight after starting on insulin?

Answer 11

• Stimulates triglyceride storage
• Inhibit lipolysis and FFA production
• Inhibit ketone production

Question 12

What is the influence of insulin on carbohydrates?

• Lier
• Muscle
• Adipose

Answer 12

• Liver: inhibit gluconeogenesis and glycogenolysis
• Muscle: increase glucose transport and glycolysis
• Adipose: same as muscle

Question 13

What is the influence of insulin on protein?

Answer 13

• Anabolic

- Increase transport of AA to liver and muscle

Question 14

What are incretins?

Answer 14

Hormones secreted into blood minutes after eating that inc. production of insulin

Question 15

What is the mechanism of sulfonylureas?

Answer 15

• Close ATP sensitive K channels in beta cell plasma membrane
• Initiate cascade resulting in insulin release

Question 16

What do we measure clinically in patients with severe recurrent hypoglycaemia?

Answer 16

C peptide

High insulin and low C peptide

Question 17

In the Kreb cycle ____ is oxidised for energy

Answer 17

Acetyl CoA

Question 18

How are free fatty acids metabolised?

Answer 18

• Cannot enter Kreb cycle

- Mostly metabolised in liver and muscle to ketone bodies

Question 19

What are three ketones produced in the body?

Answer 19

• Acetoacetate
• Acetone
• Beta hydroxybutyrate

Question 20

Which ketone can be measured clinically?

Answer 20

• Beta hydroxybutyrate

Question 21

What is the pathophysiology of diabetic ketoacidosis?

Answer 21

• Lack of insulin, so no glucose in cells (no energy source)
• Glucose accumulates in blood stream
• Activation of hormone sensitive lipase -> lipolysis
• Also breakdown of glycogen

Question 22

What are the clinical findings of a patient with diabetic ketoacidosis?

Answer 22

• Very high blood sugar
• Severe acidosis
• Hypotensive
• Volume depleted

Question 23

What is the range of normal fasting glucose?

Answer 23

3.5-5.5 mmol/L

Question 24

What happens when diabetics become hypoglycemic?

Answer 24

• ANS activated ~3.0mmol/L

- NA release - sweating, tremor, increased HR, dilated pupils etc.

Question 25

Which hormones are most important in the counter regulation of hypoglycaemia?

Answer 25

• Adrenaline and glucagon

Also cortisol.

Question 26

What are four causes of hypoglycaemia?

Answer 26

• Insulin in diabetic patients
• Sulphnylurea therapy
• Insulinoma
• Severe hormone deficiency e.g. Addison’s disease