L16: diabetes as a metabolic disorder

Question 1

What happens when there is no insulin to the liver?

Answer 1

E.g., after a meal, glucose can still enter hepatocytes via GLUT2, however it won’t be converted into glycogen.
Glycogen breakdown is no longer inhibited, so it is broken down and increasing hepatocytes glucose levels
Proteins broken down due to no insulin mediated inhibition
Increased glycogenolysis

Question 2

What happens when there is no insulin to the adipocytes?

Answer 2

No insulin means no GLUT4 inserted into the membranes, so glucose can’t get into muscle cells. So ECF glucose will be high but low in cells.
Inhibiting lipolysis does not occur so fats are broken down into fatty acids and glycerol.

Question 3

What happens where there is no insulin to the muscle?

Answer 3

Increased extracellular glucose due to no GLUT4

Breakdown of protein to amino acids as substrates for gluconeogenesis (leads to muscle wasting)

Question 4

How do fatty acids cause ketogenesis?

Answer 4

Increased circulating FA’s directed to the liver are used in beta oxidation, releasing energy and acetyl CoA. High amounts of acetyl CoA inhibits the citric acid cycle and acetyl CoA is pushed towards ketogenesis. Ketone bodies are acidic.

Question 5

Why are polyuria and dehydration caused by uncontrolled diabetes?

Answer 5

When glucose levels raise they exceed the renal threshold for renal resorption so glycosuria and osmotic diuresis occurs.

Question 6

Why does uncontrolled diabetes cause infection?

Answer 6

Due to impaired cellular immune response

Question 7

Why does weight loss and muscle and fat wasting occur due to uncontrolled diabetes?

Answer 7

Energy wasting through intracellular unavailability and loss through glycosuria.

Question 8

Why does ketosis, confusion and coma occur due to uncontrolled diabetes occur?

Answer 8

Due to acidosis, dehydration and electrolyte disturbance.

Question 9

Treatment of uncontrolled diabetes (rehydration)

Answer 9

Rehydration with intravenous saline because fluid deficit may be massive,

Question 10

Treatment of uncontrolled diabetes (insulin)

Answer 10

Infusion or regular injections

Question 11

Treatment of uncontrolled diabetes (monitoring electrolytes)

Answer 11

Insulin activates sodium potassium ATPases, so high insulin amounts being given can lead to hypokalaemia (lots of potassium ends up inside cells)
Insulin can kill patients because of its ability to acutely suppress plasma potassium concentrations.