Lecture 24: Diabetes

Question 0

Diabetes is not a single disease, what types of diabetes does it include?

Answer 0

Diabetes insipidus
Diabetes mellitus (insulin dependent and non insulin dependent)
Gestational diabetes
Bronze diabetes- occurring as a secondary effect in other diseases

Question 1

What is diabetes?

Answer 1

A disorder of metabolism

Question 2

What is bronze diabetes?

Answer 2

A form of diabetes which occurs as a secondary event in other diseases

Due to haemochromatosis which is a hereditary disease

Results in a combination of pigmented (bronze) skin and glucose intolerance

Question 3

What are the early symptoms of diabetes?

Answer 3

Polydipsia, polyuria, blurred vision and extreme fatigue also occurs

Question 4

What is diabetes insipidus?

Answer 4

Rare deficiency of ADH

ADH regulates reabsorption of water in the kidney.

Deficiency of ADH results in an inability to produce concentrated urine

This results in chronic water diuresis

Question 5

What can diabetes insipidus be treated with?

Answer 5

Administration of ADH (vasopressin)

Question 6

Which part of the brain does diabetes insipidus affect?

Answer 6

It is a disease of the posterior pituitary. (Cause unknown)

Question 7

Although the cause of disease to the posterior pituitary is unknown, what are some hypothesised causes of diabetes insipidus?

Answer 7

Trauma or brain tumours which compress the adjacent pituitary gland

Sporadic/familial mutations in the vasopressin-neutrophin II gene

Mutations in the vasopressin receptor or transporter protein genes in the kidney

Question 8

What is diabetes mellitus characterised by?

Answer 8

Fluctuations in blood glucose due to a deficiency in either insulin production or decreased effect of insulin.

Question 9

What does fluctuations of blood glucose levels cause?

Answer 9

Hyperglycaemia

Fasting glucose >7.8mmol/L
2hour Postprandial glucose >11mmol/L

Question 10

What does excessive glucose in the blood result in?

Answer 10

Hyperosmosis

Question 11

What are body fluids with high sugar content diluted by?

Answer 11

Water from low sugar-containing body compartments

Question 12

What does this dilution due to excessive blood glucose result in?

Answer 12

Dehydration of body tissues.

Question 13

How is plasma volume maintained if excessive blood glucose is high?

Answer 13

Increased fluid excretion by the kidney (polyuria)

Question 14

How is the excessive excretion of water and dehydration of tissues compensated by?

Answer 14

Increased thirst and hence increased fluid intake (polydipsia)

Question 15

Why is blurred vision often the first sign of fluctuating glucose levels?

Answer 15

Because large variations in osmosis alter the curvature of the lens

Question 16

What is type 1 DM.

Answer 16

Insulin dependent diabetes mellitus

Due to insufficient levels of insulin

Autoimmune disease trigger by something in the environment, but also evidence of genetic disposition

Question 17

What is type 2 diabetes mellitus?

Answer 17

Non insulin dependent diabetes
Due to insufficient effect of insulin in peripheral tissues as well as insufficient insulin production in response to increased demand like a high energy diet

Question 18

What happens to glucose normally after a meal?

Answer 18

Glucose is absorbed and delivered via the bloodstain to the liver.

Some blood also passes through the pancreas

Pancreas will detect high glucose in the blood and release insulin in response

The liver up takes and stores glucose as glycogen

Circulating levels of glucose are controlled from 10mM after a meal to 2mM within 2 hours

Question 19

What happens when glucose levels are low (have been absorbed etc)

Answer 19

As glucose is used up peripherally this results in lowered blood sugar levels

The liver responds by converting glycogen to glucose

This is then released in the blood for body tissues to use