micro and macro vascular complications Flashcards
what are the micro and macro vascular complications of diabetes?
micro:
retinopathy
neuropathy
nephropathy
macro:
cerebrovascular disease
ischaemic heart disease
peripheral vascular disease
what is the relationship between HbA1c and risk of microvascular complications?
the extent of hyperglycaemia (judged by HbA1c) is strongly associated with increased risk of developing microvascular complications
target HbA1c to reduce risk of micro complications is
53 mmol/mol
you should aim to be below this but that can be quite hard
how is hypertension related to risk of microvascular complications?
clear relationship
as systolic BP rises, risk of MI and microvascular complications increases in people with T1DM and T2DM
<130/80 mmHg
what two main factors should be controlled to reduce risk of microvascular complications?
HbA1c <53 mmol/mol
blood pressure
what are other factors that relate to development of microvascular complications?
duration of diabetes (gets bad above 40 years)
smoking - endothelial destruction
genetic factors (develop complications despite reasonable glycaemic control)
hyperlipidaemia
hyperglycaemic memory - inadequate glycaemic control early in in disease can result in higher risk of microvascular complications later, even with improved HbA1c
what are the mechanisms of damage in 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, and ischaemia
what is diabetic retinopathy?
main cause of:
visual loss in people with diabetes
blindness in people of working age
the early stages of retinopathy are asymptomatic
:. screening is needed
aim of screening: detect retinopathy early when it can be treated before it causes visual disturbance/loss
:. there is annual retinal screening for all diabetes patients in the UK
what does a normal retina look like?
look up pictures
optic disc appears as a light circle towards one edge
blood vessels emerging from near optic disc and extending round the eye
macula (aka fovea, responsible for central, high resolution, colour vision) appears as a darker circle in the middle
what are the 4 stages of retinopathy?
background retinopathy
pro-proliferative retinopathy
proliferative retinopathy
maculopathy
each is progressively worse
what is background retinopathy?
hard exudates (cheese colour, lipid) micro aneurisms (appear as white dots) blot haemorrhages
some white dots
some red dots or splodges
what is pre-proliferative retinopathy?
cotton wool spots (aka soft exudates)
these represent retinal ischemia
still has red splodges, haemorrhages from background retinopathy
larger ares of white dots/splodges, these are the cotton wool spots
what is proliferative retinopathy?
visible new vessels
can be on disc or elsewhere in retina
the new blood vessels appear due to all the previous damage, but they are very friable
what is maculopathy?
same disease as background retinopathy but it happens to be near the macula
hard exudates / oedema near the macula
can be cotton wool spots too
this can threaten vision
what is the treatment associated with each stage of retinopathy?
throughout: HbA1c <53 mmol/mol, BP <130/80 mmHG
background retinopathy: continued annual screening
pro proliferative retinopathy: if left alone will proceed to next stage
so early panretinal photocoagulation
proliferative retinopathy: panretinal photocoagulation
diabetic maculopathy:
oedema - anti VEGF injections directly into the eye
grid photocoagulation
(VEGF: vascular endothelial growth factor. so anti VEGF stops one of the inflammatory cause and prevents formation of new vessels)
what is pan-retinal photocoagulation?
photo coagulation: burn through areas where there is new vessel formation, stops vision from getting worse
looks like little round burns
it stops new vessels from forming and any further haemorrhage
affects peripheral vision
why is diabetic nephropathy important?
associated with progression to end stage renal failure requiring haemodialysis (although not a certainty)
healthcare burden
associated with an increased risk of cardiovascular events
how is diabetic nephropathy diagnosed?
progressive proteinuria (urine albumin:creatinine ratio - ACR)
increased blood pressure
deranged renal function (eGFR)
advanced: peripheral oedema
FIRST SIGN is microalbuminuria: >2.5 mg/mmol
and then raised creatinine and declining eGFR come later
proteinuria = ACR >30 mg/mmol
nephrotic range= >3000 mg/24hr
but this is uncommon
what is the mechanism of diabetic nephropathy?
diabetes leads to hypertension and hyperglycaemia
–> glomerular hypertension
–> proteinuria
–> glomerular and interstitial fibrosis
–> glomerular filtration rate decline
–> renal failure
what is the renin angiotensin system (RAS) and how is it blocked?
angiotensin produced by liver
renin, produced by kidneys, turns it to angiotensin I
ACE turns angiotensin I to angiotensin II
effects of Angiotensin II:
vasoconstriciton
aldosterone production from zona glomerulosa of adrenal cortex
effectively raises blood pressure
this system is in overdrive in diabetic nephropathy
angiotensin II acts via angiotensin receptors
ACE inhibitors (ACEi) are antihypertensives which block ACE
angiotensin receptor blockers (ARBs) are antihypertensives
how is diabetic nephropathy related to RAS?
blocking the RAS with and ACEi (-pril) or ARB (-sartan) reduces blood pressure and progression of diabetic nephropathy
all diabetes patients with microalbuminuria/proteinuria should be on an ACEi/ARB even if they arent hypertensive
(there is no benefit of having an ACEi and ARB simultaneously)
how is microalbuminuria related to CVD?
microalbuminuria leads to increased risk of:
ischemic stroke
myocardial infarction
all cause mortality
how is diabetic nephropathy managed?
aim for tighter glycaemic control
ACEi or ARB as soon as microalbuinuria is detected iven if patient is normotensive
reduce BP (<130/80 mmHg) usually through ACEi/ARB
stop smoking
start on an SGLT-2 inhibitor if T2DM?
what is diabetic neuropathy?
diabetes mellitus is the most common cause of neuropathy and therefore lower limb amputation
small vessels supplying the nerves are called vasa nervorum
neuropathy results when vasa nervorum get blocked
amputation may because people cant feel their feet when they are wounded
longest nerves supply the feet, so more common here
commonly glove and stocking distribution - peripheral neuropathy
can be painful
what are the risk factors of diabetic neuropathy?
age duration of diabetes poor glycaemic control height (longer nerves in the lower limbs of tall people) smoking presence of diabetic retinopathy
what is diabetic foot check?
all people with diabetes should get an annual foot check
looks for:
foot deformity, ulceration
assess sensation (monofilament, ankle jerks)
assesses foot pulses (dorsalis pedis and posterior tibial)
there is an increased risk of ulceration inpatients with:
reduced sensation to feet (peripheral neuropathy)
poor vascular supply to feet (peripheral vascular disease) (need blood to heal)
how is diabetic foot disease managed?
peripheral neuropathy: 1. regular inspection of feet by patient 2. good footwear 3. avoid barefoot walking podiatry and chiropody if needed
peripheral neuropathy with ulceration:
- multidisciplinary diabetes foot clinic
- offloading
- revascularisation if concomitant PVD
- antibiotics if infected
- orthotic footwear
- amputation if all else fails
what is mononeuropathy?
another neuropathy that is sometimes seen in diabetes
usually sudden motor loss.
eg wrist drop or foot drop
cranial nerve palsy:
double vision due to 3rd nerve palsy
what is autonomic neuropathy?
damage to sympathetic and parasympathetic nerves innervating GI tract, bladder, cardiovascular system
GI tract:
delayed gastric emptying - nausea and vomiting ( can make prandial short acting insulin challenging)
constipation/nocturnal diarrhoea
cardiovascular:
postural hypertension - can be disabling, collapsing on standing
cardiac autonomic supply - sudden cardiac death
what are the macrovascular complications?
ischaemic heart disease
cerebrovascualr disease
peripheral vascular disease
treatment targeted ti hyperglycaemia alone has a minor effect on these
it requires aggressive management of multiple risk factors
risk increased with age
true for both T1DM and T2DM
what are the risk factors for macrovascular complications?
non modifiable: age sex (women have a protective effect before menopause) birth weight FH/genes
modifiable: dyslipidaemia hypertension smoking diabetes mellitus central obesity
how is cardiovascular risk managed in diabetes?
support quitting smoking
blood pressure:
<140/80 mmHg, <130/80 if microvascular complications
lipid profile - total chol <4, LDL<2
weight - discuss lifestyle intervention +/- pharmacological treatments
annual urine microalbuminuria screen - risk factor for CVD
