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Endocrinology > Microvascular Complications of Diabetes Mellitus > Flashcards

Microvascular Complications of Diabetes Mellitus Flashcards

1
Q

State the three main sites of microvascular complications.

A
  1. Retinal arteries (retinopathy)
  2. Glomerular arterioles (nephropathy)
  3. Vasa vasorum (neuropathy)- tiny blood vessels that supply nerves
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2
Q

What factors correlate with risk of microvascular and macrovascular complications?

A
  1. Glycaemic control (HbA1c)
  2. Hypertension
  3. Hyperglycaemic memory - poor diabetes control even briefly will give an increased risk
  4. Genetics
  5. Tissue damage - through originally reversible and later irreversible alterations in proteins
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3
Q

Describe the mechanism of glucose damage to blood vessels.

A

Hyperglycaemia leads to oxidative stress and hypoxia

This triggers an inflammatory cascade, which leads to damage

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4
Q

What instrument is used to look into the eye?

A

Fundoscope

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5
Q

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

A

The optic disc is nasal to the macula

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6
Q

What are the 4 types of diabetic retinopathy?

A
  1. Background
  2. Pre-proliferative
  3. Proliferative
  4. Maculopathy
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7
Q

What three features do you see in background diabetic retinopathy?

A
  1. Hard exudates
  2. Microaneurysms - small blood vessels bulge
  3. Blot haemorrhages - blots of blood
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8
Q

What are hard exudates caused by?

A

Leakage of lipid contents makes the back of the eye look a cheesy colour

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9
Q

Describe pre-proliferative diabetic retinopathy.

A

Soft exudates (cotton wool spots)

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10
Q

What do soft exudates indicate?

A

Retinal ischaemia

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11
Q

Describe proliferative diabetic retinopathy.

A

Involves the formation of visible new vessels (in response to retinal ischaemia) on disc or elsewhere in retina

The new vessels are generally more fragile and can bleed at any time

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12
Q

Describe maculopathy.

A

Presence of hard exudates in the macula
This is the same disease as background diabetic retinopathy, it’s just that the hard exudates are in the macula
This can threaten direct vision

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13
Q

What are the steps taken in managing background diabetic retinopathy?

A

Improve blood glucose control

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14
Q

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

A

-suggests general ischaemia so to stop it progressing

need Pan-retinal photocoagulation (laser to retina)

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15
Q

Describe the treatment of maculopathy.

A

You need a grid of photocoagulation in the affected area (aim to limit damage to the macula so you don’t do pan-retinal photo coagulation)

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16
Q

State some histological glomerular features of diabetic nephropathy.

A
  1. Mesangial expansion
  2. Basement membrane thickening
  3. Glomerulosclerosis (hardening of the capillaries)
    - if there is no retinopathy, any CKD cannot be due to diabetes, these come together
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17
Q

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

A

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

18
Q

State 3 clinical features of diabetic nephropathy.

A
  1. Hypertension
  2. Progressively increasing proteinuria
  3. Progressively deteriorating kidney function
19
Q

What is the normal range for proteinuria?

A

< 30 mg/24hr

20
Q

Why do patients with diabetic nephropathy get oedematous?

A

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

21
Q

Describe some strategies for intervention of patients with diabetic nephropathy.

A
  1. Improve blood glucose control
    - the lower the Hb1ac, the lower the microvascular complications
  2. Blood pressure control
    - control of blood pressure will slow down the deterioration of kidney function
  3. Inhibition of the activity of the renin-angiotensin system
  4. Stopping smoking
22
Q

What effect does angiotensin II have on endothelial cells?

A

It makes endothelial cells more rigid

23
Q

Where is renin produced?

A

Juxtaglomerular apparatus

24
Q

What can stimulate renin release?

A

Low renal perfusion (i.e. low blood pressure)

25
Q

Where is ACE found?

A

Lungs

26
Q

State some drug target sites in the renin-angiotensin system.

A
  1. Drugs blocking renin activity
  2. ACE inhibitors
  3. Angiotensin II receptor blockers (ARBs)
27
Q

What causes diabetic neuropathy?

A

Occlusion of the vasa vasorum

28
Q

State 6 different types of diabetic neuropathy.

A
  1. Peripheral polyneuropathy
  2. Mononeuropathy
  3. Mononeuritis multiplex
  4. Radiculopathy
  5. Autonomic neuropathy
  6. Diabetic amyotrophy
29
Q

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

A
  • affects longest nerves that supply the feet and result in loss of sensation can lead to damage going unnoticed like stepping on a nail
  • more common in tall people
  • leads to loss of ankle jerks and loss of vibrational sense, multiple fractures (Charcot joints)
  • investigate w monofilament examination
30
Q

What is mononeuropathy?

A
  • usually sudden motor loss e.g. wrist drop or foot drop

- can also cause cranial nerve palsy

31
Q

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

A

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

32
Q

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

A

There would be fixed pupil dilation

This is because the parasympathetic fibres would also be affected

33
Q

What is mononeuritis multiplex?

A

A random combination of peripheral nerve lesions

34
Q

What is radiculopathy?

A

Pain over SPINAL nerves

Usually affecting a dermatome on the abdomen or chest wall

35
Q

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

A

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

36
Q

What are the effects of autonomic neuropathy on the CVS?

A

Postural hypotension

Cardiac autonomic death- can have sudden cardiac death

37
Q

How can you check for autonomic neuropathy?

A

Measure changes in heart rate in response to Valsalva manoeuvre (should have a change in HR)
Look at an ECG and compare the R-R intervals

38
Q

What are the four mechanisms of glucose damage?

A

Polyol pathway
AGEs
Protein kinase C
Hexosamine

39
Q

What is the relationship between Diabetic retinopathy and vision?

A

Diabetic retinopathy is the main cause of visual loss in people with diabetes and the main cause of blindness in people of working age

40
Q

Explain how cranial nerve palsy results in double vision

A
  • double vision due to 3rd nerve palsy (down and out_
  • lateral rectus - abducens - OUT
  • superior oblique - trochlear- DOWN
  • pupil does respond to light
41
Q

What is autonomic neuropathy?

A

Loss of SNS and PNS nerves to GI tract, bladder and CVS

Endocrinology (18 decks)

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