Microvascular complications of diabetes Flashcards
What is the relationship between diabetes and blood vessels?
Diabetes damages blod vessels
What are the sites of microvascular complications?
Retinal arteries (diabetic retinopathy) Glomerular arteries (nephropathy) Vasa vasorum (tiny blood vessels that supply the nerves- neuropathy)
What factors affect the risk of microvascular complication?
Severity of hyperglycaemia Hypertension Genetic Hyperglycaemic memory- poor diabetes control Tissue damage
What is the main cause of blindness in people of working age?
Diabetic retinopathy
What do you look at an eye with?
Fundoscope
Where is the optic disc when you look at an eye?
Yellow ring in the nasal part of the eye
Where is the macula?
Dark ring more lateral to fovea (middle of image)
What are the 4 types of retinopathy?
Background
Pre-proliferative
Proliferative
Maculopathy
How does background diabetic retinopathy present?
You get hard exudates which appear as cheesy yellow spaces in the retina
Microaneurysms which can rupture causing blot haemorrhages
What causes the hard exudates in background diabetic retinopathy?
Leakage of lipid contents
How does pre-proliferative diabetic retinopathy present?
Cotton wool spots called soft exudates which show retinal ischaemia
How does proliferative diabetic retinopathy present?
It involves formation of new vessels which can be in optic disc or elsewhere, they form as a response to retinal ischaemia, they are fragile and can bleed easily
How does maculopathy present?
Hard exudates near the macula (same disease as background just exudates are at macula)
This can threaten direct vision
How do you treat background retinopathy?
Improve control of blood glucose and warn patient
How do you treat pre-proliferative and proliferative?
Pan-retinal photocoagulation
What is pan-retinal photocoagulation?
Laser the retinal and stop the vessels from bleeding
Why do you not use pan-retinal photocoagulation for maculopathy?
Only a problem at macula so you only need a grid in affected area
What are the features of diabetic nephropathy?
Hypertension
Progressively increasing proteinuria
Progressively deteriorating kidney function
Which histological sites are affected by nephropathy?
Glomerular
Vascular
Tubulointerstitial
What glomerular changes occur?
Mesangial expansion
Basement membrane thickening
Glomerulosclerosis
What do the changes in the glomerulus cause?
Glomerulus becomes less flexible and harder- absorption of nutrients can change so you can get more pressure going through kidneys which can lead to changes in blood pressure
What are the stimuli for glomerusclerosis and secondary effects on tubulointerstitium?
Prolonged exposure to high glucose or glycosylated proteins in at risk patients
How common is diabetic nephropathy in both types of diabetes?
20-40% after 30-40 years in both
What affects the epidemiology of diabetic nephropathy in T2DM?
Age at development of disease
Racial factors
Cardiovascular morbidity
What are the clinical features of diabetic nephropathy?
Progressive proteinuria
Increased blood pressure
Deranged renal function
What is the normal range of protein in urine?
<30mg/24hrs
What is the nephrotic range of protein in urine?
> 3000mg/24hrs
How is protein in the urine measured?
Urine dipsticks
What happens as urinary excretion of albumin increases?
Their serum albumin will be low so they will become quite oedematous
What are the strategies for intervention of nephropathy?
Diabetic control
Blood pressure control
Inhibition of activity of renin-angiotensin system
Stopping smoking
What actions of angiotensin make endothelial cells more rigid?
Vasoactive effects Mediation of glomerular hyper filtration Increased tubular uptake of proteins Induction of profibrotic cytokines Stimulation of glomerular and tubular growth Podocyte effects Induction of pro-inflammatory cytokines etc
What produces renin?
Juxtaglomerular apparatus
When do renin levels increase?
If you have low perfusion (blood pressure)
Where is ACE found?
Lungs
What is diabetes the most common cause of as a result of being the most common cause of neuropathy?
Lower limb amputation
What are the vasa vasorum?
Small blood vessels supplying the nerves
What are the 6 types of diabetic neuropathy? (at Parties, Marilyn Manson Regularly Abuses Drugs)
Peripheral polyneuropathy Mononeuropathy Mononeuritis multiplex Radiculopathy Autonomic neuropathy Diabetic amyotrophy
What does peripheral neuropathy affect?
Hands and feet
What sort of people is peripheral neuropathy more likely to affect?
Tall patients
Patients with poor glucose control
How do you test for peripheral neuropathy?
Monofilament expansion- prick the patients foot with a filament
What does peripheral neuropathy lead to?
Loss of sensation
Loss of ankle jerks
Loss of vibrational sense
How does mononeuropathy normally present?
Sudden motor loss- wrist or foot drop
Cranial nerve palsy
What normally happens to the eye in pupil sparing third nerve palsy?
The eye is usually down and out because of unopposed action of lateral rectus and superior oblique and the pupil responds to light
Where are the parasympathetic fibres in the eye and why is this important?
On the outside so they don’t lose blood supply in diabetes
What happens when an aneurysm causes third nerve palsy?
It will press on the parasympathetic fibres first causing a fixed dilated pupil which is how you know that it’s not due to diabetes
What is mononeuritis multiplex?
Random combination of peripheral nerve lesions
What is radiculopathy?
Pain over spinal nerves usually affecting a dermatome on abdomen or chest wall
What is autonomic neuropathy?
Loss of sympathetic and parasympathetic nerves to the GI tract, bladder and cardiovascular system
What are the effects of autonomic neuropathy on the GI tract?
Difficulty swallowing
Delayed gastric emptying
Constipation/nocturnal diarrhoea
Bladder dysfunction
What are the effects of autonomic neuropathy on the cardiovascular system?
Postural hypotension
Cardiac autonomic supply- sudden cardiac death
How do you check for autonomic neuropathy?
Measure changes in heart rate in response to valsalva manoeuvre (make them blow into a tube which normally causes a change in heart rate)
