17. Microvascular complications Flashcards
(34 cards)
what are the common sites of microvascular complication?
- retinal arteries
- glomerular arteries (kidneys)
- vasa nervorum (blood vessels that supply nerves)
when does the incidence of microvascular disease increase?
when BP increases
what is the mechanism of glucose damage?
hyperglycaemia and hyperlipidaemia cause age-rage, oxidative stress and hypoxia which lead to inflammatory signalling cascades, resulting in local activation of pro-inflammatory cytokines that causes inflammation in the eyes, kidneys and nerves
which pathways make glucose damage worse?
- polyol pathway
- AGEs
- Protein Kinase C
- hexosamine
what is the main cause of visual loss in people with diabetes and of working age?
diabetic retinopathy
what does background diabetic retinopathy involve?
- hard exudates (cheese colour, lipid)
- microaneurysms (“dots”)
- blot haemorrhages
patients have leakage of protein through the vessels
what happens to background diabetic retinopathy if diabetes is not controlled and what does this involve?
pre-proliferative diabetic retinopathy resulting in ischaemia of the retina
- soft exudates (cotton wool spots)
what happens to to pre-proliferative diabetic retinopathy if it is not treated and what does this involve?
proliferative retinopathy resulting in the formation of new vessels within the retina
- visible, new vessels which can affect vision or bleed (haemorrhage)
what is maculopathy?
- specific type of retinopathy which affects colour vision (hard exudates near macula)
- can cause severe visual impairment and threaten direct vision
how is diabetic retinopathy managed?
- background DR is managed by improving blood glucose control
- pan retinal photocoagulation can be done to burn off parts of the retina to prevent the change to pre-proliferative and proliferative DR
- laser beams are targeted to parts of the retina undergoing change to prevent vessel formation
how is maculopathy managed?
as maculopathy only affects the macula a grid of photocoagulation is done instead of burning the whole retina
what is the most common cause of kidney problems?
diabetes
what are the histological features of diabetic nephropathy?
- glomerular changes
- vascular changes
- tubulointerstitial changes
what glomerular changes occur in diabetic nephropathy?
- mesangial expansion
- basement membrane thickening
- glomerulosclerosis
what is the epidemiology of diabetic neuropathy?
- T1DM: 20-40% will have nephropathy after 30-40 years
- T2DM complications occur between 60-70
- racial factors predispose individuals to complications
what are the clinical features of diabetic nephropathy?
- progressive proteinuria
- increased BP
- deranged renal function
what are the proteinuria ranges?
- normal range: <30mg/24hrs
- microalbuminiruc range: 30-300mg/24hrs
- assymptomatic range: 300-3000mg/24hrs
- nephrotic range: >3000mg/24hr
what are the effects of proteinuria?
- hypoalbuminaemia because increased protein loss in urine = less protein in blood
- oedema
what are the 4 types of intervention for diabetic nephropathy?
- diabetes control
- BP control
- inhibition of activity of the renin-angiotensin system
- stopping smoking
what are the roles of angiotensin 2?
- vasoactive effects
- mediation of glomerular hyperfiltration
- increased tubular uptake of proteins
- induction of pro-fibrotic cytokines
- stimulation of glomerular and tubular growth
- podocyte effects
- upregulation of adhesion molecules on endothelial cells
- upregulation of lipoprotein receptors
- induction of pro-inflammatory cytokines
- stimulates fibroblast proliferation
what can an outcome of diabetic neuropathy be?
lower limb amputation
what changes are seen in diabetic neuropathy?
- peripheral polyneuropathy
- mononeuropathy (one nerve affected)
- mononeuritis multiplex
- radiculopathy (dermatomes affected)
- autonomic neuropathy
- diabetic amyotrophy (muscle affected)
what causes neuropathy?
the blockage of small vessels supplying nerves called vasa nervorum
what does peripheral neuropathy involve?
- the longest nerves are affected in the body (those supplying feet)
- this results in a loss of sensation
- more common in tall people
- patients cannot sense an injury to the foot
