Endo - Micro/Macrovascular Risk of DM Flashcards
What are the microvascular complications of DM?
→ retinopathy
→ nephropathy
→ neuropathy
What is the relationship between Hb1Ac and risk of microvascular complications?
→ increasing Hb1Ac = increasing risk
→ Hb1Ac < 53 mmol/mol
What is the relationship between BP and risk of microvascular complications?
→ increasing BP = increasing risk
What factors influence risk of MicroV complications in DM?
→ Hb1Ac > 53 mmol/mol → elevated BP → duration of diabetes → smoking - endothelial dysfunction → genetic factors → hyperlipidaemia → hyperglycaemic memory
What is the mechanism of damage in hyperglycaemia + hyperlipidemia?
→ 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
What is the main cause of visual loss in DM + blindness in people of working age?
diabetic retinopathy
Why is screening very important in diabetic retinopathy?
→ early stages of retinopathy are all asymptomatic
→ detect retinopathy early when it can be treated before visual loss + disturbances occur
How often do people with diabetes get screened for diabetic retinopathy?
annually
What does a normal retina without retinopathy look like?
→ macula : central high resolution, colour vision
→ optic disc
What are the stages of progression of diabetic retinopathy?
→ background retinopathy
→ pre-proliferative retinopathy
→ proliferative retinopathy
→ maculopathy
What are the characteristics of background retinopathy?
→ hard exudates (cheese colour, lipid)
→ micro-aneurysms (‘dots”)
→ blot haemorrhages
What are the characteristics of pre-proliferative retinopathy?
→ Cotton wool spots also called soft exudates
→ Represent retinal ischaemia
What are the characteristics of proliferative retinopathy?
Visible new vessels on disc or elsewhere in retina
What are the characteristics of maculopathy?
→ Hard exudates / oedema near the macula
→ Same disease as background, but happens to be near macula
→ This can threaten vision
How is background retinopathy treated?
→ continued annual surveillance
→ improve Hb1Ac, stop smoking, lipid lowering, good BP control
How is pre-proliferative retinopathy treated?
start early pan-retinal photocoagulation
→ if left alone, will progress to new vessel growth
How is proliferative retinopathy treated?
pan-retinal photocoagulation
How is maculopathy treated?
→ grid photocoagulation
→ oedema treated with anti-VEGF injections directly into the eye
What is VEGF?
vascular endothelial growth factor
What is pan-retinal photocoagulation?
burn the new growth of blood vessels to reduce risk of haemorrhaging and therefore reduce risk of visual disturbances, etc.
What is diabetic nephropathy is important?
→ associated with progression to end-stage renal failure requiring haemodialysis
→ healthcare burden
→ associated with increased risk of cardiovascular events
What are signs of diabetic nephropathy clinically + phsyically?
→ progressive proteinuria (albumin: creatinine ration > 30mg/mmol) → increased blood pressure → deranged renal function (eGFR) → microalbuminuria > 2.5 mg/mmol → advanced: peripheral oedema
What is a side effect of pan-retinal photocoagulation?
causes loss of peripheral vision
What is the mechanism of diabetic nephropathy?
→ hyperglycaemia + hypertension from diabetes → glomerular hypertension → proteinuria → glomerular + interstitial fibrosis → GFR decline → renal failure
How can diabetic nephropathy be treated?
→ ACE inhibitors
→ Angiotensin Receptor Blockers (ARBs)
How do ACE inhibitors work?
→ antihypertensives
→ blocks ACE from catalysing angiotensin I to angiotensin II
→ inhibits aldosterone production in zona glomerulosa of adrenal cortex
→ reduces BP + progression of diabetic nephropathy
How do ARBs work?
→ antihypertensives
→ angiotensin receptors are blocked
→ inhibits aldosterone production in zona glomerulosa of adrenal cortex
→ reduces BP + progression of diabetic nephropathy
Why aren’t ACEi and ARBs prescribed together?
no benefit is using both simultaneously
How is diabetic 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
What is neuropathy?
→ Small vessels supplying nerves are called vasa nervorum
→ Neuropathy results when vasa nervorum get blocked
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 → Presence of diabetic retinopathy
Where is neuropathy most common in the body? Why?
→ commonly glove + hand distribution (peripheral neuropathy)
→ longest nerves supply feet, so more common in feet
Why is neuropathy dangerous?
→ can be painful
→ danger is that patients don’t sense injuries to feet (e.g. stepping on nail)
Why do diabetic patients get annual foot checks?
high risk of foot ulceration (and foot injuries in general) due to :
→ diabetic neuropathy = reduced sensation in feet
→ peripheral vascular disease = poor vascular supply to feet
What is looked for in an annual foot check for DM?
→ foot deformity, ulceration
→ Assess sensation (monofilament, ankle jerks)
→ Assess foot pulses (dorsalis pedis + posterior tibial)
How is peripheral neuropathy managed?
→ Regular inspection of feet by affected individual
→ Good footwear
→ Avoid barefoot walking
→ Podiatry and chiropody if needed
How is peripheral neuropathy with ulceration managed?
→ Multidisciplinary diabetes foot clinic (podiatrist, etc.) → Offloading (bed rest, etc.) → Revascularisation if concomitant PVD → Antibiotics if infected → Orthotic footwear → Amputation if all else fails
What are some other types of neuropathy?
→ mononeuropathy
→ autonomic neuropathy
What are the characteristics of mononeuropathy?
→ usually sudden motor loss e.g. wrist drop, foot drop
→ cranial nerve palsy (double vision + 3rd nerve palsy (eyes look down + out))
What is autonomic neuropathy?
damage to sympathetic + parasympathetic nerves innervating GI tract, bladder, cardiovascular system
How does autonomic neuropathy affect the GI tract?
→ Delayed gastric emptying: nausea and vomiting (can make prandial short-acting insulin challenging)
→ Constipation / nocturnal diarrhoea
How does autonomic neuropathy affect the cardiovascular system?
→ Postural hypotension: can be disabling e.g. collapsing on standing.
→ Cardiac autonomic supply: sudden cardiac death
What are the macro-vascular complications of DM?
→ cerebrovascular disease
→ ischaemic heart disease
→ peripheral vascular disease
Why can’t the macro-vascular complications of DM be treated solely by treating the hyperglycaemia?
→ treatment targeted to hyperglycaemia alone has minor effect on increased risk of cardiovascular disease
→ prevention of macro-vascular disease requires aggressive management of multiple risk factors
What is the trend in males and females and their diabetic cardiovascular mortality?
increased mortality compared to no DM
What are the non-modifiable risks of macro-vascular disease?
→ age
→ sex
→ birth weight
→ genetics
What are the modifiable risks of macro-vascular disease?
→ Dyslipidaemia → Hypertension → Smoking → Diabetes mellitus → Central obesity
How is cardiovascular risk managed in DM?
→ 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 with or without pharmacological treatments
→ Annual urine microalbuminuria screen – risk factor for cardiovascular disease
