One of the leading complications associated with diabetes is blindness or other eye diseases stemming from vascular damage to the eyes caused by high blood sugar. Diabetic retinopathy, the most common form of diabetes eye condition, is caused by damage of the retinal blood vessels. This damage causes the ruptured vessels to leak fluid, restricting oxygen and blurring sight. As the disease progresses, the eye tries to form new vessels on the surface of the retina, which may also bleed or obscure sight by their mere presence. Diligently controlling blood sugar is a major means of preventing or at least slowing the onset and progression of diabetic retinopathy.
In diabetics, the vitreous body of the eye has been found to change more rapidly than with just normal aging. These changes have been implicated in functional disturbances and retinal detachment. The vitreous body is composed of a fine network of hyaluronan gel, collagen, proteoglycans and fibronectin, all of which are susceptible to free radical damage brought on by light and UV damage and glycation.44
A growing body of research shows that oxidation induced by glycation can wreak havoc on the eye. Protein glycation occurs when sugar molecules inappropriately bind to protein molecules, forming crosslinks that distort the proteins and consequently render them useless. Glycation appears to increase oxidative processes, which may explain why both glycation and oxidation simultaneously increase with age. High blood sugar also increases glycation activity, which may also explain the various kinds of tissue damage that characterize advanced diabetes.
Even before an individual is officially diagnosed with Type II diabetes, high serum insulin levels can induce retinopathy. Overweight individuals at risk for Type II diabetes should have their fasting insulin levels checked to guard against a pre-diabetic state (characterized by hyperinsulinemia) that can severely damage the eyes. By following a low glycemic diet, excess serum insulin can be reduced.
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Adapted with permission from an article in Life Extension, Feb 2003