Endocrinology 5 - Diabetes Mellitus

Question 1

How does glucose move into muscle and adipose tissue?

Answer 1

Via the GLUT-4 protein. Insulin recruits + stimulates transporters from the cytoplasm to move to the membrane.

Question 2

What is the structure of the GLUT-4 protein?

Answer 2

Has a hydrophobic outer embedded to the membrane and a hydrophilic core, which allows glucose into the cell.

Question 3

What are the effects of insulin on the liver?

Answer 3

1. Increased protein synthesis.
2. Decreased protolysis.
3. Inhibits gluconeogenesis.

Question 4

What are the effects of insulin on adipocytes?

Answer 4

1. Breaks down fats in the blood so they can enter the adipocytes (lipoprotein lipase stimulated by insulin) into glycerol.
2. Promotes formation of triglyceride and fat using glucose.
3. Inhibits lipolysis.

Question 5

What is a simple indicator of someone’s risk of ischaemic heart disease?

Answer 5

Their waist circumference - omental fat.

Question 6

How is glycerol used by the liver?

Answer 6

1. Make triglycerides (enters lipoprotein particles).

2. Gluconeogenesis (2 glycerols = glucose).

Question 7

What fuel can the brain use and what cannot it use?

Answer 7

Can use glucose and ketone bodies. Cannot use fatty acids.

Question 8

What is the effect of insulin on ketone bodies?

Answer 8

Insulin inhibits the conversion of fatty acyl CoA to ketone bodies. (glucagon does opposite)

Question 9

What increases gluconeogenesis in the liver?

Answer 9

1. Cortisol.
2. Somatotrophin.
3. Catecholamines.
4. Glucagon.

Question 10

What promotes the conversion of fatty acyl CoA to ketone bodies?

Answer 10

Glucagon.

Question 11

What are ketone bodies?

Answer 11

Three water-soluble molecules produced by the liver from fatty acids during periods of low food intake:

1. Acetone.
2. Acetoacetic acid.
3. Beta-hydroxybutyric acid.

Question 12

What is the effect of insulin on glycogenolysis?

Answer 12

Insulin promotes the storage of glucose as glycogen (Glucose => Glucose-6-phosphate => glycogen).

Question 13

What promotes glycogenolysis?

Answer 13

1. Glucagon.

2. Catecholamines.

Question 14

What is the effect of insulin on glucose uptake by muscle cells?

Answer 14

Promotes uptake of glucose via GLUT-4. Glucose is then stored as glycogen.

Question 15

What inhibits uptake of glucose via GLUT-4 in muscle cells?

Answer 15

Stress hormones.

Question 16

In a fasted state, what is your insulin:glucagon ratio and what does this result in?

Answer 16

Low insulin to glucose ratio.
Increase in protolysis, lipolysis, gluconeogenesis + glyconeolysis (HGO). Ketogenesis after prolonged time.
Decrease in AA concentration after a prolonged time.

Question 17

In a fed state, what is your insulin:glucagon ratio and what does this result in?

Answer 17

High insulin to glucagon ratio.
Increase in protogenesis, lipogenesis and glycogen.
Decrease in protolysis, glucogenesis (stop HGO).

Question 18

What happens during insulin induced hypoglycaemia?

Answer 18

Increase in insulin, glucagon, catecholamines, cortisol and somatotrophin.
Decrease in HGO and lipolysis.

Question 19

What happens during T2DM?

Answer 19

Increase in LDL cholesterol, triglyceride and circulating NEFA.
Decrease in lipoprotein lipase activity, VLDL clearance and HDL cholesterol.

Question 20

How do you distinguish between T1DM and T2DM?

Answer 20

T2DM has enough insulin to suppress ketone production and to stop protolysis. Therefore if glucose + ketone are high = T1DM.

Question 21

What are the 2 pathways affected by insulin?

Answer 21

1. Mitogenic pathway (MAPK).

2. Metabolic pathway (PI3K-Akt).

Question 22

Which pathway has insulin resistance?

Answer 22

The metabolic pathway.

Question 23

What types of tissue does insulin resistance reside in? (3)

Answer 23

1. Liver tissue.
2. Muscle tissue.
3. Adipose tissue

Question 24

What is compensatory hyperinsulinaemia?

Answer 24

Someone with insulin resistance making more insulin to maintain normal blood glucose.

Question 25

How does high insulin harm a person?

Answer 25

Has an increased effect on the mitogenic pathway (MAPK).

Question 26

How much the diet be controlled to manage T2DM?

Answer 26

Reduce fat, refined carbohydrates and sodium.

Increase complex carbohydrates and soluble fibre.

Question 27

What are the features of someone with insulin resistance? (9)

Answer 27

1. Hypertension.
2. High triglyceride.
3. Low HDL.
4. High LDL.
5. Fasting blood glucose > 6.0mmol/l.
6. Adipocytokines.
7. Inflammatory state.
8. Energy expenditure affected.
9. High Omental fat.