Lecture 9: Microvascular complications Flashcards
HbA1c gives indication of the average glucose has been for ____ months
2-3 months
Describe the epidemiological factors for retinopathy between patients with diabetes
Some people have a predisposition to the microvascular complications than others.
Not just down to glucagemia control
What are the acute complications for type 1 diabetes
–Ketoacidosis
–Hypoglycaemia
What are the chronic macrovascular complications for type 1 diabetes
- Ischaemic heart disease
- Peripheral vascular disease
- Cerebrovascular disease
What are the chronic microvascular complications for type 1 diabetes
- Retinopathy
- Neuropathy
- Nephropathy
Describe the conventional regiment for insulin
2 injections per day
Injection in the morning (mixing of fast and medium acting insulin)
Take a second injection at teatime (mixing of fast and medium acting insulin)
Describe the intestive regiment for insulin
4 injections per day
Intermidate to long acting insulin given in the morning to give the bolus insulin
Fast acting insulin given after each meal
There are two regiments for insulin injection: conventional and intestive.
Conventional involves ___ injections per day. Intestive involves _____ per day. ____ is more flexible.
A) 2 injections
B) 4 injections
C) Intestive
Which insulin regiment (intestive/conventional) can help to prevent microvascular disease
Intestive
The pathogenesis of microvascular complications associated with diabetes can be split into two major causes.
Name these causes?
- Capillary damage
- Metabolic damage
Microvascular damage:
Takes a few years to develop in T_DM
May be present at diagnosis in T_DM
A) Type 1
B) Type 2
Describe the polyol pathway?
- Two-step process that converts glucose to fructose
- Glucose is reduced to sorbitol, which is subsequently oxidized to fructose.
Describe how the polyol pathway can cause the microvascular complications of diabetes
- While most cells require the action of insulin for glucose to gain entry into the cell, the cells of the retina, kidney, and nervous tissues are insulin-independent, so glucose moves freely across the cell membrane. The cells will use glucose for energy as normal, and any glucose not used for energy will enter the polyol pathway.
- When blood glucose is normal this interchange causes no problems, as aldose reductase has a low affinity for glucose at normal concentrations.
- In a hyperglycemic state, the affinity of aldose reductase for glucose rises, causing sorbitol to accumulate, and using more NADPH, leaving less NADPH for other processes of cellular metabolism.
- Excessive activation of the polyol pathway increases intracellular and extracellular sorbitol concentrations, increased concentrations of reactive oxygen species, and decreased concentrations of nitric oxide and glutathione. Each of these imbalances can damage cells; in diabetes there are several acting together.
While most cells require the action of insulin for glucose to gain entry into the cell, some cells are insulin-independent, so glucose moves freely across the cell membrane, regardless of insulin.
Name the cells that are insulin-independent?
The cells of the retina, kidney, and nervous tissues are insulin-independent
Which chronic microvascular complication is the hallmark of diabetic complications
Retinopathy
People having a ____ insulin regiment have a higher risk of microvascular complications
Conventinal
What are the early stages for retinopathy, diabetes complication
- Hyperglycaemia
- Damage to small vessel wall
- Microaneurysms
- When vessel wall is breached
- Dot haemorrhages- blood leaking out into the retina
- Protein and fluid left behind
- Hard exudates
- Micro-infarcts as the pressure builds up from the blood
- Cotton wool spots
What are the later stages for retinopathy, diabetes complication
- Damage to veins
- Venous budding
- Blockage of blood supply
- Ischaemia→ VEGF and other growth factors
- Neovascularisation- new blood vessels start to form to bypass the blockage
- Proliferative retinopathy
- Vitreous haemorrhage - new blood vessels are very fragile and at risk of haemorrhaging
- Fluid not cleared from macular area
- Macular oedema
How can a diabetic prevent retinopathy?
•Manage the risk factors such as:
- Good glycaemia control
- Stop smoking
- Good blood pressure control
What is the treatment for diabetic retinopathy?
–Address risk factors
–Ophthalmic review
- Laser
- VEGF inhibitors (bevacizumab)
- vitrectomy - drain away the blood that is building up
Retinal screening is done every ____ years after the age of ___ for diabetes
A) one year
B) 12 years old
Name the four stages of diabetic nephropathy
- Renal enlargement and hyperfiltration
- Microalbuminuria
- Macroalbuminuria
- End stage kidney failure
Renal enlargement and hyperfiltration stage of diabetic nephropathy?
- The renal hypertrophy (increase in size) causing an increase in GFR.
- The afferent arteriole vasodilates causing:
- Decrease glomerular pressure
- Thickened GBM
- Capillary damage
- Shear stress on endothelial cells
- The result of these changes is the failue of the glomerulus to act as a filter causing leakage of protein into urine
Define microalbuminuria
- Tiny traces of albumin in the urine
- Too small to be detected on Dipstick
- Important in diabetes as it is used as the early detection for nephropathy allowing us to help to prevent progression to macroalbuminuria
