Diabetes Microvascular Complications (half of one lecture) Flashcards
Name some things diabetes is the most common cause of…
- Blindness in ages 20-74
- Kidney failure
- Non-traumatic leg amputations
- 2-4x higher death rates due to heart disease
- 7th leading cause of death in USA
What are the 3 most common microvascular complications of diabetes?
retinopathy, nephropathy, neuropathy
–>result of hyperglycemia
What is the mechanism for hyperglycemia-induced tissue damage?
Not completely understood. Involves genetic factors, repeated acute changes in cellular metab and cumulative long-term changes in stable macromolecules due to hyperglycemia, leading to tissue damage. Also involves independent accelerating factors like hypertension, hyperlipidemia etc
What are the 2 major categories of diabetic retinopathy?
- Non-proliferative (NPDR)
2. Proliferative (PDR)
When is the ave onset of retinopathy in type 1 vs type 2?
Type 1: obset 2-5 yrs after diagnosis, nearly everyone affected by 20 yrs
Type 2: 20% at the time of diagnosis, obset 4-7 years prior to diagnosis. 50-80% incidence at 20 yrs
Describe the pathophys of retinopathy
Hyperglycemia–>dysreg retinal blood flow–>inc inflammation/oxidative stress, edema (inc vasc permeability), ischemia (microthrombosis), proliferation of new bvs
-hypertension, dyslipidemia and meds are also risk factors
Describe the genetics of retinopathy
Inc incidence in 1st deg relatives, associated with nephropathy in T1D pts
Macular edema
- Thickening of the retina
- Accounts for 75% of vision loss due to diabetes
- Can occur at any stage of retinopathy and is clinically significant
What is mild NPDR?
- Microaneurysms (small areas of dilated arteries), dot hemorrhages, and/or hard exudates (lipid leakage from within macrophages in the retina)
- 5% annual progression to PDR
What is moderate/severe NPDR?
- Findings of mild NPDR plus…
- Soft exudates (cotton wool spots caused by nerve fiber layer infarcts), venous beading, intraretinal microvascular abnormalities (occluded vessels, dilated and tortuous capillaries)
- Moderate: 15% annual progression PDR
- Severe: 50-75% progression
How do we diagnose macular edema?
Req specialized fundoscopic exam
What is the key characteristic of PDR?
Neovascularization
-new bvs are fragile and can easily rupture. Rupture results in hemorrhage
What can proliferative retinopathy lead to?
- Neovascularization
- Preretinal and vitreous hemorrhage
- Acute vision loss, often resolves spontaneously - Fibrosis
- Retinal traction and detachment - Ischemia
How should retinopathy be prevented?
- Glycemic control (highly effective in primary prevention–T1D–via metabolic memory as well, somewhat helpful at slowing progression of NPDR in T2D, more helpful with T1D)
- Antihypertensive therapy
- Maybe with lipid lowering, antiplatelet agents or carbonic anhydrase inhibitors
How do we treat retinopathy ?
- NPDR with clinically significant macular edema (CSME): focal laser photocoagulation
- High-risk and severe PDR: panretinal photocoagulation and medical therapy: Intravitreal glucocorticoids, VEGF inhibitors
- Vitrectomy indications: nonclearing vitreous hemorrhage, traction retinal detachment involving fovea, severe PDR not responsive to PRP
Describe epidemiology of nephropathy
Most common cause of kidney failure in US
- Onset 5-20 yrs after diabetes
- Independent risk factor for both CV and overall mortality
What are the risk factors for nephropathy?
- Poor glycemic control
- Hypertension
- Age
- Genetic factors
- Race (AAs, Pima Indian, Mexican-American)
- Obesity
- Tobacco use
- Other microv disease like retinopathy
What are the pathologic changes in nephropathy?
Glomerular disease
-mesangial expansion, basement membrane thickening, sclerosis
Albuminuria (protein in urine)
- Microalbuminuria (high albuminuria)–»30-300mg/g creatinine
- Proteinuria (macro/very high albuminuria)–»300mg/g creatinine
How does nephropathy progress?
First, inc glomerular filtration. Then microalbuminuria develops with progression to proteinuria or, if control it, regression to normoalbuminuria. If didn’t control it, net result is a decrease in kidney fxn/GFR and progression to end=stage kidney failure
How do we prevent nephropathy?
- Glycemic control
- BP control
- Treatment of dyslipidemia
- Measurement of spot urine microalbumin to creatine ratio
What is the treatment of nephropathy?
- ACE inhibitor/Angiotensin II receptor blocker (first line, dilate efferent arteriole to reduce glomerular pressure)
- Other antihypertensive agents
- Dietary restriction (no sodium, protein)
- Weight loss
- All in addition to glucose control
Epi of neuropathy
- Most common microvascular complication
- 50-70% lifetime incidence of at least one form of neuropathy
Most common type of diabetic neuropathy?
-Diabetic polyneuropathy (peripheral neuropathy) is the most common type
List the risk factors for neuropathy
- Age
- Duration of dis
- Poor glucose control
- BV damage
- Mechanical injury to nerves
- Genetic susceptibility
- Hypertension
- Dyslipidemia/hyperTGs
- Tobacco use
- Excessive alc use
