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Microvascular complications

The microvascular complications are retinopathy, nephropathy and
neuropathy all of which are characterised by non-inflammatory dam-
age to the cells in question and progressive loss of function in the
respective organs and systems.

Retinopathy is the most frequent cause of new cases of blindness
among adults aged 20-74 years of age. It is caused by damage to
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the capillary endothelial cells in the retina and risk factors include dura-
tion of T2DM, hypertension, and smoking. During the first two decades
64
of diabetic disease, 60% of patients with T2DM develop some degree
of retinopathy, which is often accompanied by glaucoma, cataracts
and macular disease or other eye disorders, all of which occur earlier
and more frequently in people with this disease. Diabetic retinopathy
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is often linked with diabetic nephropathy. Diabetic nephropathy is dis-
65
cussed in detail in Chapter 2, suffice to say here that it is a progressive
kidney disease caused by changes in glomerular structure and func-
tion and expansion of extracellular matrix and that approximately one-
third of all people with T2DM have some degree of renal impairment. 66
Neuropathy is characterised by a progressive decline predominantly
in sensation, but also in movement and other bodily functions due to
damage of the neurons and their insulating Schwann cells. Neuro-
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pathy is broadly divided into peripheral and autonomic. The former
is impaired sensation in the legs, feet, arm or hands – often accom-
panied by pain, carpal tunnel syndrome and erectile dysfunction, while
67
the latter is characterised by problems with breathing, blood pressure,
bladder control, vision and the gastrointestinal tract (e.g. gastroparesis).
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Neuropathy is a significant source of morbidity and mortality in people
with diabetes and T2DM is the leading cause of this condition in the
Western world. Recent studies have found that peripheral neuropathy
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affects approximately 70% of people with T2DM. 69 70 Other studies have
shown that peripheral nerve damage is a factor in 76% of all diabetic
foot ulcers, implicating this T2DM complication in 50-75% of all non-trau-
matic amputations. 68 71 Ulcers and amputations as a consequence of
diabetes-induced peripheral neuropathy are a huge problem. Some
estimates suggest that every 30 seconds a lower limb is lost somewhere
in the world as a consequence of diabetes. The mortality rate in those
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diabetic patients with new-onset ulceration of the feet is 43%–55%. In
those people who undergo an amputation, this rises to almost 75% – a
mortality rate that is higher than several types of cancer. 73-79

Needless to say, the burden of foot complications due to diabetes-
induced peripheral neuropathy is huge. Economic analyses have sug-
gested that the cost of treating diabetic foot ulcers in Europe alone
may be as high as €10 billion per year. For all its debilitating and eco-
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