Diabetes Mellitus: Insulin action

Question 1

<p>Which Glucose transporter does insulin stimulate?</p>

Answer 1

<p>GLUT-4</p>

Question 2

<p>Where are GLUT-4 receptors in the absence of insulin?</p>

Answer 2

<p>In vesicles in the cytoplasm</p>

Question 3

<p>What happens to GLUT-4 receptors when there is an increase in insulin levels?</p>

Answer 3

<p>They are recruited to the plasma membrane resulting in a 7-fold increase in glucose uptake</p>

Question 4

<p>Describe the structure of GLUT-4:</p>

Answer 4

<p>Hydrophobic outside, with hydrophilic ring on inside</p>

Question 5

<p>What is the effect of insulin on protein?</p>

Answer 5

<p>Insulin stops proteolysis and increases the re-sysnthesis of proteins</p>

Question 6

<p>What is the effect of cortisol on proteins?</p>

Answer 6

<p>Increases proteolysis</p>

Question 7

<p>What is the effect of insulin on the liver?</p>

Answer 7

<p>Inhibits gluconeogenesis</p>

Question 8

<p>What is the effect of insulin on adipocytes?</p>

Answer 8

<p>Increases hydrolysis of triglycerides in blood by lipoprotein lipase
Increases formation of triglycerides in adipocytes</p>

Question 9

<p>What can glycerol be made into in the liver?</p>

Answer 9

<p>Triglycerides

| Glucose</p>

Question 10

<p>Can the liver make glucose from fatty acids?</p>

Answer 10

<p>Nope</p>

Question 11

<p>What can the brain use as respiratory substrates?</p>

Answer 11

<p>Glucose
Ketone bodies

Cannot use Fatty acids</p>

Question 12

<p>How are ketone bodies made and where?</p>

Answer 12

<p>Non-esterified fatty acids broken down into:
acetone
acetoacetate and 
3-hydroxybutyrate 
in Liver</p>

Question 13

<p>When blood glucose is too low to support the brain, what happens?</p>

Answer 13

<p>Glucagon stimulates ketone body formation</p>

Question 14

<p>What is the insulin deficiency test?</p>

Answer 14

<p>Measure levels of ketones and glucose in urine.

| If both high together, insulin deficient </p>

Question 15

<p>What hormone triggers hepatic glycogenolysis?</p>

Answer 15

<p>Glucagon</p>

Question 16

<p>What is significant about glucose that enters muscle?</p>

Answer 16

<p>Cannot be removed, must be either respired or stored as glucagon by that muscle</p>

Question 17

<p>Describe the fasted state:</p>

Answer 17

<p>•Low Insulin:Glycogen ratio
•Blood glucose concentration is NORMAL because the change in Insulin:Glucagon ratio maintains a normal blood glucose concentration
•Muscle use lipid
•Brain uses glucose and then, at a later stage, ketone bodies
•INCREASE IN:
-Concentration of NEFA
-Proteolysis
-Lipolysis
-Hepatic Glucose Output (from glycogenolysis and gluconeogensis)
•DECREASE IN:
-Amino Acid Concentration (when prolonged)</p>

Question 18

<p>Describe the fed state:</p>

Answer 18

<p>•High Insulin:Glucagon ratio
•Stored insulin is released then you get 2nd phase insulin release
•Stop Hepatic Glucose    Output
•INCREASE IN:
-Glycogen
-Protein Synthesis
-Lipogenesis
•DECREASE IN:
-Gluconeogenesis
-Proteolysis</p>

Question 19

<p>Describe the presentation of T1D:</p>

Answer 19

<p>Absolute insulin deficiency leading to:

- Loss of muscle mass due to proteolysis
- Lipolysis
- High Hepatic glucose output, so goes to kidney and not fully reabsorbed; glycosuria and ketonuria</p>

Question 20

<p>Describe insulin induced hypoglycaemia:</p>

Answer 20

<p>High concurrent insulin AND glucagon levels, causing glucose top continue entering muscle.
Glucagon will eventually trump insulin, but IM glucagon can be given</p>

Question 21

What is dyslipidaemia?

Answer 21

Abnormal amount of lipids in the blood

Question 22

What are the two pathways effected by insulin?

Answer 22

Metabolic pathway (PI3K-Akt)
Mitogenic Pathway (MAPK)

Question 23

Which pathway does insulin resistance lie in?

Answer 23

Metabolic pathway

Question 24

What does initial insulin resistance cause?

Answer 24

Compensatory Hyperinsulinaemia, so increased stimulation of the MAPK pathway, so smooth muscle hypertrophy leading to hypertension; reduced ovarian function and abnormal clotting

Question 25

Describe the presentation of T2D:

Answer 25

Insulin resistance with 60-80% obese and dyslipidaemia

Later insulin deficiency with hyperglycaemia

Has less osmotic symptoms yet has complications

Likely to present late with complications unlike T1DM as that is caught earlier

Question 26

How should someone with T2D eat?

Answer 26

Controlling of total calories, reducing calories as fats/refined carbohydrates

Increasing calories as complex carbohydrates

Increasing soluble fibre and decreasing sodium