microvascular comp diabetes Flashcards
site of microvascular complications
retinal arteries
renal glomerular arterioles
vasa nervorum - tiny blood vessels that supply nerves
what can be used to approximate risk of microalbuminuria, neuropathy, nephropathy, retinopathy
HbA1c (mmol/mol)
factors relating to development of microvascular complications
- severity of hyperglycemia
- hypertension
- genetic factors
- hyperglycaemia memory
- duration/glucose variability?
mechanism of damage
hyperglycaemia/lipidemia leads to:
- AGE-RAGE/ oxidative stress/ hypoxia
- inflammatory signalling cascades
- local activation of pro-inflammatory cytokines
- inflammation
- nephropathy, retinopathway, neuropathy
what is the main cause of visual loss in people with diabetes and the main cause of blindness of people of working age?
diabetic retinopathy
what kind of symptoms do you get in the early stages of diabetes?
asymptomatic
- visual issues due to osmotic changes in lens early on in diagnosis
increased vascular permeability in diabetic retinopathy causes what?
- retinal neovascularisation
- diabetic macular oedema
where do the blood vessels emerge from in the eye?
the optic disc
stages of retinopathy
- background retinopathy
- preproliferative retinopathy
- proliferative retinopathy
- maculopathy
background retinopathy features
- hard exudates (lipid looks like cheese)
- microaneurysms (dots)
- blot haemorrhages
preproliferative retinopathy features
- cotton wool spots - soft exudates
- > represent retinal ischaemia
proliferative retinopathy features
- visible new vessels over the disc (neovascularisation)
maculopathy features
- hard exudates/ oedema near macula
- same disease as background but near macula
- can threaten vision
treatment for retinopathy
- improve HbA1c
- improve BP
pan-retinal photocoagulation
- burning eye vessels to stop neovascularisation (for proliferative nephropathy)
How can we treat diabetic maculopathy?
anti-VEGF injections directly into eye (vascular endothelial growth factor)
- grid photocoagulation
maculopathy can threaten what?
direct vision
features of diabetic nephropathy: (4)
- hypertension
- progressively increasing proteinuria
- progressive decline in kidney function
- classic histological features
anyone with diabetes at risk of it
how is albumin recorded
expressed as a ratio to creatinine
why is nephropathy important?
- assocaited with progression to end stage renal failure requiring haemodialysis
- healthcare burden
- associated with increased risk of cardiovasc events
histological features of nephropathy
- mesangial expansion (glomerular changes)
- basement membrane thickening
- glomerulosclerosis
epidemiology of nephropathy
20-40% of T1DM have it after 30-40 years
T2DM similar but depends on age at development of disease, ethnic differences, age at presentation,
diagnosis of nephropathy
- progressive proteinuria
- increased blood pressure
- deranged renal function
- advanced peripheral oedema
managing nephropathy
- manage BP (aim for <130/80 mmHg) with ACEi or ARBs
- Give ACEi/ARB even if normotensive as soon as they have microalbuminuria
- Stop smoking
- tighter glycaemic control
- SGLT-2 inhibitor if T2DM (not official guidance)
why does RAS blockage work?
In diabetes the RAS system is in overdrive
Blocking RAS with ACE inhibitors or ARBs (angiotensin 2 receptor blocker) reduces BP and progression of diabetic nephropathy
No benefit of giving ACEi/ARB simultaneously- end up with K problems
what makes neuropathy happen?
- vasa nervorum blocked
- nerves don’t get blood supply
commonest manifestation of diabetic neuropathy
- in feet (longest nerves supply feet)
- Glove and sock distribution- peripheral neuropathy
- loss of sensation (issues with ulceration and DFD)
clinical features of peripheral neuropathy
- loss of sensation
- loss of vibration sense
- loss of temperature sensation
- loss of proprioception
- loss of ankle jerks
- ## glove and stocking distribution
management (prevention) of peripheral neuropathy
- regular inspection of affected feet
- good footwear
- avoid barefoot walking
management of peripheral neuropathy with ulceration
- Multidisciplinary diabetic foot clinic
- offloading ( a term generally understood as relieving pressure from an ulcerated area. )
- revascularisation if concomitant peripheral vascular disease
- Antibiotics if infected
- orthotic footwear
- amputation if all else fails
other neuropathies
- mononeuropathy e.g. cranial (III) nerve palsy
- mononeuritis multiplex
- radiculopathy (SN)
- autonomic neuropathy
What is autonomic neuropathy?
Damage to sympathetic and parasympathetic nerves innervating GI tract, bladder and cardiovascular system
Symptoms: Delayed gastric emptying causing nausea and vomiting Constipation / nocturnal diarrhoea Postural hypotension Sudden cardiac death
what symtpoms let you know you’re developing diabetic nephropathy?
- asymptomatic
- detected by screening
Aim of screening is to detect it early when it can be detected- annual retinal screening in UK for diabetic patients
How is the endothelium affected in microvascular complications?
Increased formation of mitochondrial superoxide free radicals in the endothelium
Generation of glycated plasma proteins to form advanced end products (AGEs)
Damaged endothelium leads to leaky capillaries and ischaemia
what does vascular endothelial dysfunction lead to?
- retinal ischaemia
- vascular permeability
diabetic mechanism of renal failure?
- hyperglycaemia and hypertension
- leads to glomerular hypertension
- followed by proteinuria
- then glomerular and interstitial fibrosis
- then GFR decline
- then renal failure
how to disrupt mechanism of renal failure?
hyperglycaemic treatments
- ACEi/ARB
