Micro & Macro-vasculature complications of diabetes Flashcards
What are the Microvascular complications associated with diabetes?
Retinopathy
Neuropathy
Nephropathy
What are the Macro-vascular complications of diabetes?
Cerebrovascular disease
Ischaemic heart disease
Peripheral vascular disease
What is the relationship between glycemic control and microvascular complications?
Extent of hyperglycaemia (as judged by HbA1c) is strongly associated with the risk of developing microvascular complications
What is the target HbA1c target to reduce risk of microvascular complications?
53 mmol/mol
What is the relationship between systolic BP & microvascular complications?
Clear relationship between rising systolic BP and risk of MI and microvascular complications in people with T1DM and T2DM
Therefore, prevention of complications requires reduction in HbA1c and BP control
What other risk factors are related to the development of microvascular complications?
Duration of diabetes
Smoking – endothelial dysfunction
Genetic factors – some people develop complications despite reasonable glycaemic control
Hyperlipidaemia
Hyperglycaemic memory – inadequate glucose control early on can result in higher risk of complications LATER, even if HbA1c improved
What is the mechanism of damage that leads to microvascular complications?
DO NOT NEED TO MEMORISE
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
Why is diabetic retinopathy important?
Main cause of
visual loss in people with diabetes
blindness in people of working age
The early stages of retinopathy are all asymptomatic, therefore screening is needed
What is the aim of retinopathy 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.
What is visible in Background retinopathy?
Hard exudates (cheese colour, lipid)
Microaneurysms (“dots”)
Blot haemorrhages
Needs continual annual surveillance
What is visible in pre-proliferative retinopathy?
Cotton wool spots also called soft exudates
Represent retinal ischaemia
Early panretinal photocoagulation
What is visible in proliferative retinopathy?
Visible new vessels
On disc or elsewhere in retina
Panretinal photocoagulation
What is visible in Maculopathy?
Hard exudates / oedema near the macula
Same disease as background, but happens to be near macula
This can threaten visionOedema: Anti-VEGF injections directly into the eye (VEGF: vascular endothelial growth factor)
Grid photocoagulation
What is a negative of Panretinal photocoagulation?
Patient can lose some peripheral vision
Why is diabetic nephropathy important
Associated with progression to end-stage renal failure requiring haemodialysis
Healthcare burden
Associated with increased risk of cardiovascular disease
How do you diagnose diabetic nephropathy?
Progressive proteinuria (urine albumin:creatinine ratio - ACR)
Increased blood pressure
Deranged renal function (eGFR)
Advanced: peripheral oedema
What is the cut off for Microalbuminuria?
2.5 mg/mmol
What is the threshold for Proteinurea?
Proteinuria = ACR > 30mg/mmol
What is the threshold for Nephrotic Proteinurea?
> 3000mg/24hr
What is the mechanism of action for diabetic nephropathy?
Hyperglycemia & Hypertension Glomerular Hypertension Proteinurea Glomerular and interstitial fibrosis Glomerular filtration rate decline Renal failure
What system do we want to manipulate in diabetic nephropathy?
Renin-Angiotensin System
What 2 drugs are used to treat diabetic nephropathy?
ACE inhibitor ( end in -pril)
Angiotensin 2 receptor blocker ( end in -sartan)
they reduce BP & progression of diabetic nephropathy, should be prescribed to all normotensive patients with microalbuminuria /proteinurea.
No benefit to having both
What is Microalbuminurea a risk factor for?
Cardiovascular disease
What are the management principles for diabetic nephropathy?
Aim for tighter glycemic 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?
Why is diabetic neuropathy important?
Diabetes mellitus is the most common cause of neuropathy and therefore lower limb amputation
What are the small vessels supplying nerves called?
vasa nervorum
Neuropathy results when vasa nervorum get blocked
What are the risk factors for diabetic neuropathy?
- Age
- Duration of diabetes
- Poor glycaemic control
- Height (longer nerves in lower limbs of tall people)
- Smoking
- Presence of diabetic retinopathy
Where is diabetic neuropathy most common?
Longest nerves supply feet – so more common in feet
Commonly glove & stocking distribution – peripheral neuropathy
Can be painful
Danger is that patients will not sense an injury to the foot (eg. stepping on a nail)
What would you do in an annual foot check?
- Look for foot deformity, ulceration
- Assess sensation (monofilament, ankle jerks)
- Assess foot pulses (dorsalis pedis and posterior tibial)
Which patients have an increased risk of foot ulceration?
- reduced sensation to feet (peripheral neuropathy)
- poor vascular supply to feet (peripheral vascular disease)
What is the management for Peripheral neuropathy?
- Regular inspection of feet by affected individual
- Good footwear
- Avoid barefoot walking
Podiatry and chiropody if needed
What is the management for 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?
Usually, sudden motor loss
eg wrist drop, foot drop
Cranial nerve palsy
double vision due to 3rd (oculomotor) nerve palsy
What is Autonomic neuropathy?
Damage to sympathetic and parasympathetic nerves innervating GI tract, bladder, cardiovascular system
What would happen with autonomic neuropathy of the GI Tract?
Delayed gastric emptying: nausea and vomiting (can make prandial short-acting insulin challenging)
- Constipation / nocturnal diarrhoea
What would happen with autonomic neuropathy of the Cardiovascular system?
Postural hypotension: can be disabling - collapsing on standing.
- Cardiac autonomic supply: sudden cardiac death
What are the non modifiable risk factors for macrovascular disease?
Age
Sex
Birth weight
FH/Genes
What are the modifiable risk factors for macrovascular disease?
Dyslipidaemia Hypertension Smoking Diabetes mellitus Central obesity
What are the management criteria for managing cardiovascular risk in diabetes mellitus?
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
