Endo - Diabetes microvascular complications

Question 1

State the three main sites of microvascular complications?

Answer 1

• Retinal arteries (Retinopathy)
• Glomerular arteries (nephropathy)
• Vasa vasorum (neuropathy)

Question 2

What factors correlate with risk of microvascular and macrovascular complications?

Answer 2

• Glycaemic control (HbA1c)

- Hypertension

Question 3

Describe the mechanism of glucose damage to blood vessels?

Answer 3

• Hyperglycaemia leads to oxidative stress and hypoxia

- This triggers an inflammatory cascade which causes damage

Question 4

What instrument is used to look into the eye?

Answer 4

A fundoscope

Question 5

Where is the optic disc relative to the macula on the back of the eye?

Answer 5

The optic disc is nasal to the macula - more medial

Question 6

What are the 4 types of diabetic retinopathy?

Answer 6

1. Background
2. Pre-proliferative
3. Proliferative
4. Maculopathy

Question 7

What three features do you see in background diabetic retinopathy?

Answer 7

• Hard exudates
• Microaneurysms
• Blot haemorrhages

Question 8

What are hard exudates caused by?

Answer 8

Leakage of lipid contents

Question 9

Describe pre-proliferative diabetic retinopathy?

Answer 9

• Soft exudates

- Some haemorrhages

Question 10

What do soft exudates indicate?

Answer 10

Retinal ischaemia

Question 11

Describe proliferative diabetic retinopathy?

Answer 11

• Involves formation of new vessels (in response to retinal ischaemia)
• New vessels are fragile and can bleed at any time

Question 12

Describe maculopathy?

Answer 12

• Presence of hard exudates on the macula
• Same as background diabetic retinopathy just with hard exudates on the macula
• Threatens direct vision

Question 13

What are the steps taken in managing background diabetic retinopathy?

Answer 13

Improve blood glucose control

Question 14

What is the treatment for pre-proliferative and proliferative diabetic retinopathy?

Answer 14

Pan-retinal photocoagulation:

Slows the growth of new blood vessels by laser burning the retina

Question 15

Describe the treatment for maculopathy?

Answer 15

A grid of photocoagulation in the affected area - limit to area affected to prevent pan-retinal photocoagulation

Question 16

State some histological features of diabetic nephropathy

Answer 16

• Mesangial expansion
• Basement membrane thickening
• Glomerulosclerosis (hardening of capillaries)

Question 17

In diabetic nephropathy you get over production of matrix. What can this be caused by?

Answer 17

• Effects of prolonged exposure to high glucose or glycosylated proteins
• A rise in pressure within the glomerular capillaries
• Angiotensin II

Question 18

State 3 clinical features of diabetic nephropathy

Answer 18

• Progressive proteinuria
• Increased blood pressure
• Deranged renal function

Question 19

What is the normal range for proteinuria?

Answer 19

< 30mg/24hr

Question 20

Why do patients with diabetic nephropathy get oedematous?

Answer 20

1. Increased proteinuria means they are losing albumin through their urine
2. This decreases serum albumin hence decreases the osmotic potential of the plasma so less fluid is drawn back into the circulation

Question 21

Describe some strategies for intervention of patients with diabetic nephropathy

Answer 21

• Improve blood glucose levels
• Blood pressure control
• Inhibition of the activity of the renin-angiotensin system
• Smoking cessation

Question 22

What effect does angiotensin II have on endothelial cells?

Answer 22

It makes endotheial cells more rigid

Question 23

Where is renin produced?

Answer 23

Juxtaglomerular apparatus

Question 24

What can stimulate renin release?

Answer 24

Low renal perfusion (Low blood pressure)

Question 25

Where is ACE found?

Answer 25

Lungs

Question 26

State some drug targets sites in the renin-angiotensin system

Answer 26

- Drugs blocking renin activity - ACE inhibitors - Angiotensin II receptor blockers

Question 27

What causes diabetic neuropathy?

Answer 27

Occlusion in the vasa vasorum

Question 28

State the 6 different types of diabetic neuropathy?

Answer 28

- Peripheral polyneuropathy - Mononeuropathy - Mononeuritis multiplex - Radiculopathy - Autonomic neuropathy - Diabetic amyotrophy

Question 29

What can peripheral neuropathy lead to and how can it be tested?

Answer 29

- Loss of sensation can lead to damage going unnoticed - Loss of ankle jerks and vibrational sense - Innapropriate use of joints can lead to charcot joints

Question 30

What is mononeuropathy?

Answer 30

- Usually sudden motor loss e.g. wrist drop or foot drop | - Can also cause cranial nerve palsy

Question 31

Why is the pupil spared in pupil sparing third nerve palsy?

Answer 31

The parasympathetic fibres, that are responsible for the diameter of the pupil, run on the outside of the main nerve so they don’t lose their blood supply in diabetes

Question 32

How would an aneurysm causing third nerve palsy present differently to third nerve palsy caused by diabetes?

Answer 32

There would be fixed pupil dilation: | This is because the parasympathetic fibres would also be affected

Question 33

What is mononeuritis multiplex?

Answer 33

A random combination of peripheral nerve lesions

Question 34

What is radiculopathy?

Answer 34

- Pain over spinal nerves | - Usually affecting a dermatome on the abdomen or chest wall

Question 35

What are the effects of autonomic neuropathy on the GI tract?

Answer 35

- Difficulty swallowing - Delayed gastric emptying - Constipation/nocturnal diarrhoea - NOTE: it can also lead to bladder dysfunction

Question 36

What are the effects of autonomic neuropathy on the CVS?

Answer 36

- Postural hypotension | - There have been reports of sudden cardiac death

Question 37

How can you check for autonomic neuropathy?

Answer 37

- Measure changes in heart rate due to Valsalva manoeuvre | - Look at an ECG and compare the R-R intervals