Endo 17 - Microvascular complications of DM Flashcards
Where are the sites of microvascular complications?
Retinal arteries, glomerular arterioles (kidney), vasa nervorum (tiny blood vessels supplying nerves)
What do microvascular complications depend on?
- Severity of hyperglycaemia
- Hypertension
- Genetics
- “Hyperglycaemic memory” - initial years very important in preventing microvascular complications, and poor initial control cannot be mitigated by good present control
- Tissue damage (originally reversible, later irreversible - via alterations in proteins)
What are the mechanisms of glucose damage
- Polyol pathway
- AGEs
- Protein Kinase C
- Hexosamine
What is the main cause of blindness in people of working age and the main cause of visual loss in people with diabetes?
Diabetic retinopathy
In a normal retina, the optic disc is bright and the fovea/macula is the dark spot. In background diabetic retinopathy, what are the features
Background diabetic retinopathy:
- Hard exudates (cheese colour)
- Microaneurysms
- Blot haemorrhages
If background diabetic retinopathy isn’t treated, what happens?
What is a feature of this stage of diabetic retinopathy?
We get pre-proliferative diabetic retinopathy
- We get soft exudates - cotton wool spots (showing retinal ischaemia)
If pre-proliferative retinopathy isn’t treated, we can get proliferative retinopathy. What are features of this
- Visible new vessels - chaotic and unsmooth
2. New vessels may affect vision directly or bleed - causing visual loss
Describe maculopathy
Variant of diabetic retinopathy
Hard exudates near macula - can threaten direct vision
How is background diabetic retinopathy managed
Improve blood glucose control - warn patients that warning signs are present
How are pre-proliferative and proliferative diabetic retinopathy managed?
Pre-proliferative (cotton wool spots)= Suggests general ischaemia (if left untreated, new vessels will grow). Requires pan retinal photocoagulation - laser burns pre-proliferative parts of retina before new vessels grow
Proliferative diabetic retinopathy (visible new vessels) = requires pan retinal photocoagulation
Describe treatment/management of maculopathy
Grid-focused retinal photocoagulation
What can diabetic nephropathy result in
- Hypertension
- Proteinuria (progressively increasing)
- Progressively deteriorating kidney function
- Classic histological features
What are the histological features of diabetic nephropathy
Glomerular changes:
- Mesangial expansion
- Basement membrane thickening
- Glomerulosclerosis
Vascular changes
Tubulointerstitial changes
What are the strategies for intervention of diabetic nephropathy
- Diabetic control - decreasing HbA1c reduces microvascular complication risk
- BP control - BP rise = decline in kidney function and GFR
- Inhibition of RAS - via ACEi
- Stopping smoking
What is the most common cause of neuropathy and subsequent lower limb amputation?
Diabetic neuropathy
Occurs when small vessels supplying nerves (vasa nervorum) are blocked
Peripheral neuropathy is more likely to occur in?
Tall patients, patients with poor glucose control
Describe peripheral neuropathy - clinical signs
- Loss of ankle jerk
- Loss of vibration sense (use tuning fork)
- Multiple fractures on foot X-ray
Describe mononeuropathy
Affect 1 nerve - commonly motor nerves affected - can cause foot/wrist drop
Or CN palsy - e.g. double vision / CN3 palsy
Diabetes causes what type of 3rd nerve palsy
Pupil sparing - i.e. no dilation
If dilation - then tumour or something
Describe mononeuritis multiplex
Random combination of peripheral nerve lesions
Describe radiculopathy
Pain over spinal nerves, usually affects dermatome on abdomen or chest wall
Describe autonomic neuropathy
Loss of SNS and PNS to GIT, bladder, CVS
Difficulty swallowing, delayed gastric emptying, constipation, bladder dysfunction, postural hypotension
What are the tests that can be done for autonomic neuropathy
Measure changes in HR in response to valsalva manoeuvre
Usually change in HR - look at ECG and compare R-R interval
