Vascular complications of DM Flashcards
what are the microvascular complications of diabetes mellitus?
retinopathy
nephropathy
neuropathy
what are the macrovascular complications of diabetes mellitus?
cerebrovascular disease
ischaemic heart disease
peripheral vascular disease
Is extent of hyperglycaemia (as judged by HbA1c) associated with the risk of developing microvascular complications?
What is the target HbA1c to reduce risk of microvascular complications?
Name another factor that increases this risk
Yes, strongly
53mmol/mol (<7%)
Clear relationship between rising systolic BP and risk of MI and microvascular complications in people with T1DM and T2DM
what are the other risk factors (besides HbA1c) for complications of diabetes?
Hyperlipidaemia
Duration of diabetes
Hyperglycaemic memory – inadequate glucose control early on can result in higher risk of complications LATER, even if HbA1c improved
Smoking – endothelial dysfunction
Genetic factors – some people develop complications despite reasonable glycaemic control
Mechanism of damage of hyperglycemia leading to microvascular complications
Increased formation of mitochondrial superoxide free radicals in the endothelium
Generation of glycated plasma proteins to form advanced glycation end products (AGEs)
Activation of inflammatory pathways
Damaged endothelium results in
‘Leaky’ capillaries
Ischaemia
COmplications of diabetic retinopathy
Main cause of
visual loss in people with diabetes
blindness in people of working age
how do we aim to detect retinopathy?
What is the aim of this?
How is this acheived in the UK
through screening as early stages are asymptomatic
Aim of screening - to detect retinopathy EARLY when it can be treated before it causes visual disturbance / loss
Annual retinal screening in the UK for all diabetes patients
describe the appearance of a normal retina
optic disk bright spot visible
thin veins semi visible
macula densa visible
describe background retinopathy?
hard exudates (cheese colour, lipid)
microaneuyrsms (dots)
blot haemorrhages
enhanced blood vessels
describe pre proliferative retinopathy
Cotton wool spots also called soft exudates
Represent retinal ischaemia
More extensive haemorrhage
describe proliferative retinopathy
new vessels visible (on disc or elsewhere in retina)
describe maculopathy retinopathy
Hard exudates / oedema near the macula
Same disease as background, but happens to be near macula
This can threaten vision
General treatments to reduce risk of retinopathy
Improve HbA1c, stop smoking, lipid lowering,
good blood pressure control <130/80 mmHg
how do you treat background retinopathy?
you can’t.
annual surveillance
lifestyle changes
how do you treat pre proliferative retinopathy
If left alone will progress to new vessel growth
So, early pan-retinal photocoagulation
how do you treat proliferative retinopathy?
panretinal photocoagulation
how do you treat diabetic maculopathy?
Oedema: anti-VEGF injections directly into eye
grid photocoagulation
what are the risks of panretinal photocoagulation?
loss of some peripheral vision due to burns
Why is treating diabetic nephropathy improtant?
Associated with progression to end-stage renal failure requiring haemodialysis (healthcare burden)
Associated with increased risk of cardiovascular events
how do you diagnose diabetic nephropathy?
urinalysis (microalbuminuria >2.5mg/mmol proteinuria (ACR>30mg/mmol), nephrotic range (>3000mg/24hr))
increased blood pressure
eGFR (deranged)
what is the mechanism of diabetic nephropathy?
hypertension & hyperglycaemia–>glomerular hypertension–>progressive proteinuria (urine ACR)–> glomerular &interstitial fibrosis
glomerular filtration rate decline (eGFR)
renal failure
Advanced: peripheral oedema
What receptors does angiotensin II bind to?
Name2 classes of antihypertensives. What does each block?
Angiotensin II acts via angiotensin receptors
ACE inhibitors (ACEi) are antihypertensives which block ACE
Angiotensin receptor blockers (ARBs) are antihypertensives which block angiotensin receptors ((on adrenal cortex and vasculature))
Benefits of blocking RAAS with an ACEi/ ARB?
when are antihypertensive treatments prescribed?
Is it beneficial to have both an ACEi/ARB simultaneously
Blocking RAAS with an ACE inhibitor (‘-pril) or angiotensin 2 receptor blocker (ARB, ‘-sartan’) reduces blood pressure & progression of diabetic nephropathy
All diabetes patients with microalbuminuria/proteinuria should have an ACEi/ARB even if normotensive
No benefit to having both ACEi/ARB simultaneously
how is nephropathy managed?
Aim for tighter glycaemic control
ACEi/ARB even if normotensive as soon as patient has microalbuminuria
Reduce BP (aim <130/80 mmHg) usually through ACEi or A2RB
Stop smoking
Start an SGLT-2 inhibitor if T2DM?
What is the most common cause of neuropathy/ lower limb amputation?
Diabetes mellitus is the most common cause of neuropathy and therefore lower limb amputation
when does diabetic neuropathy occur?
when vasa nervorum get blocked (blood vessels supplying nerves)
what are the risk factors of diabetic neuropathy?
age
duration of diabetes
poor glycaemic control
height (longer nerves in lower limbs of tall people)
smoking
prescence of diabetic retinopathy
where is most common for diabetic neuropathy to show?
Longest nerves supply feet – so more common in feet
Commonly glove & stocking distribution – peripheral neuropathy
Is diabetic nephropathy painful?
What is the danger of diabetic nephropathy?
Can be painful
Danger is that patients will not sense an injury to the foot (eg. stepping on a nail)
what is included in annual foot checks?
inspection for foot deformity, ulceration
assess sensation (monofilament, ankle jerks)
assess foot pulses (dorsalis pedis, posterior tibial)
when is the risk of ulceration highest?
- reduced sensation to feet (peripheral neuropathy)
- poor vascular supply to feet (peripheral vascular disease)
Management of peripheral neuropathy without ulceration
- Regular inspection of feet by affected individual
- Good footwear
- Avoid barefoot walking
Podiatry and chiropody if needed
what is the management of peripheral neuropathy with ulceration?
multidisciplinary diabetes foot clinic
offloading
revascularisation if concomitant PVD
antibiotics if infected
orthotic footwear
amputation if needed
presentation of mononeuropathy
usually sudden motor loss (foot drop, wrist drop)
cranial nerve palsy - double vision due to 3rd nerve palsy
what is autonomic neuropathy?
damage to sympathetic & parasympathetic nerves innervating GI tract, bladder, CV system
GI effects of autonomic neuropathy
delayed gastric emptying which can lead to nausea and vomiting (makes prandial short acting insulin hard)
constipation/nocturnal diarrhoea
how is the CV system affected by autonomic neuropathy?
postural hypertension (collapsing on standing, can be disabling)
cardiac autonomic supply causing sudden cardiac death
What effect does treatment targeted to hyperglycemia alone have on risk of macrovascular complications?
What does this mean?
Treatment targeted to hyperglycaemia alone has minor effect on increased risk of cardiovascular disease
Prevention of macrovascular disease requires aggressive management of multiple risk factors
what are the non-modifiable risk factors for macrovascular complications of DM?
age
sex
birth weight
FH/genetics
what are the modifiable risk factors for macrovascular complications of DM?
dyslipidaemia
hypertension
diabetes mellitus
smoking
central obesity
how is CV risk in DM managed?
Smoking status – support to quit
Blood pressure < 140/80 mmHg, < 130/80 mmHg if microvascular complication (NB often needs multiple agents)
Lipid profile – total chol <4, LDL <2
Weight – discuss lifestyle intervention +/- pharmacological treatments
Annual urine microalbuminuria screen – risk factor for cardiovascular disease.
