Endocrinology - Diabetic Complications

Question 1

describe the classification of diabetic retinopathy

Answer 1

1) Non-proliferative DR
i. Mild: at least 1 microaneurysm
ii. Moderate: microaneurysms, blot haemorrhages, hard exudates and some cotton wool spots, venous beading/looping and intraretinal microvascular abnormalities (IRMA)
iii. Severe: blot haemorrhages and microaneurysms in 4 quadrants, venous beading in at least 2 quadrants, IRMA in at least 1 quadrant

2) Proliferative DR (more common in T1DM, 50% blind in 5 yrs)
- neovascularisation: new vessels on the disc (NVD) or within 1 disc diameter of it - new vessels elsewhere (NVE)
- fibrous tissue forming anterior to retinal disc

Question 2

why does neovascularisation occur in proliferative DR? what is the significance of this?

Answer 2

As retina becomes more ischaemic, new BVs may arise from optic disc or in periphery of retina.

New vessels are fragile and bleed easily - pre-retinal haemorrhage.
As the new vessels mature, connective tissue and fibrosis (gliosis) occurs, allowing vitreous to exert traction which may cause retinal detachment. It detachment extends across the fovea, vision will be lost.

Most often occurs in T1DM - 50% blind n 5 yrs.

Question 3

what are hard exudates and cotton wool spots?

Answer 3

• hard exudates = precipitates of lipoproteins leaking from retinal blood vessels
• cotton wool spots = local ischaemia leads to disruption of axoplasmic flow - build up of axonal debris

Question 4

what are the features of diabetic maculopathy?

Answer 4

Based on location rather than severity, anything is potentially serious. Involves:

• focal or diffuse macular oedema
• thickening of retina
• hard exudates

Cause decreased visual acuity.

Question 5

describe 2 main reasons why DM increases risk of foot ulceration

Answer 5

1. Peripheral neuropathy results in Charcot foot:
   
   • lack of protective sensation against pressure and heat… repeated trauma (e.g. from ill-fitting shoes)
   • motor fibre abnormalities… dev. of anatomical deformities (e.g. arched foot, clawing of toes) - contributes to dev. of infection
2. PAD: ischaemia results in skin fragility and impaired healing

Question 6

describe the presentation of a diabetic foot ulcer

Answer 6

PAINLESS ulceration that tends to occur in areas:

• most subjected to weight bearing, e.g. heal, plantar metatarsal head areas, tips of prominent toes (usually 1st or 2nd)
• most subjected to stress, e.g. malleoli

Question 7

how would you manage a pt with diabetic foot ulcer?

Answer 7

1. optimisation of blood glucose and PAD control
2. offloading wound using appropriate therapeutic footwear
3. daily saline or similar dressing to provide moist wound environment
4. debridement when necessary
5. antibiotic therapy if cellulitis/osteomyelitis present (take cultures before), e.g. co-amoxiclav if mild, ceftriaxone/tazocin/vancomycin if severe

Question 8

what is the most common autonomic neuropathy in DM?

Answer 8

orthostatic hypotension

Question 9

describe possible effects of GI autonomic neuropathy

Answer 9

1. gastroparesis: erratic blood glucose control, bloating and vomiting. Management inc.: metoclopramide, domperidone or erythromycin (prokinetic agents).
2. Chronic diarrhoea: often occurs at night.
3. GORD: causedd by decreased lower oesophageal sphincter pressure