Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: Quantumcat on 20/05/2003 16:50:25
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If anyone knows of any good articles about diabetes-caused eye damage, I need it for a friend! Your help is appreciated!
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I can certainly tell you a little bit about it.
Diabetes is a metabolic syndrome characterised by a relative or absolute deficiency of the peptide hormone insulin which leads to hyperglycaemia (elevated blood sugar levels). Insulin switches on cellular 'transporters' which move glucose into cells. Without it cells cannot pick up sugar from the blood, fooling the body into thinking that it is fasting and leading to the mobilisation of energy stores in the form of fatty acids.
Absolute insulin deficiency characterises type 1 (insulin-dependent) diabetes which is most often seen in people with young-onset disease and is caused by immune-mediated destruction of the pancreatic insulin-secreting cells in the islets of Langerhans. The seasonal and geographical variation in prevalence has led to the implication of certain viruses which are believed to provoke the immune system to inappropriately attack the pancreas. Individuals with type 1 DM inject themselves daily with insulin under the skin.
Type 2 diabetes (non insulin-dependent diabetes mellitus - a misleading term since some people with this condition also require supplemental insulin injections) is also called maturity-onset diabetes and commonly runs in families. It is often associated with obesity and is a condition of insulin insensitivity rather than insulin deficiency. In obese individuals it is almost as though their cells have become deaf to the insulin signal since they often have much higher than normal insulin levels which are required to keep blood sugar normal. Eventually the pancreas cannot sustain such an exhaggerated insulin output and the levels begin to fall, allowing blood sugar to rise and triggering diabetes. This condition can be treated with drugs called sulphonylureas (taken by mouth) to boost the production of insulin from the pancreas and biguanides (such as metformin) which can increase uptake of glucose into cells. A newer family of drugs (the glitazones including rosiglitazone) switch on genes which are involved in metabolism and can help to regulate lipid levels and boost glucose utilisation.
Both of these diseases are united by the consequence of insulin deficiency - chronically elevated glucose levels and a deranged lipid profile which, over time, adversely affect blood vessels and can lead to under-supply of blood to certain crucial body areas including the kidney, retina and nervous system.
In the eye, deficient blood flow to the retina (the tissue with the highest metabolic rate in the body) triggers the formation of new blood vessels as the retinal tissue desperately tries to boost its supply of oxygen. But the new vessels develop in a disorganised way and are weak and fragile and prone to leaking which can cause a haemorrhage into the retina. If this occurs within the central field of vision blindness can ensue. For this reason doctors use lasers to burn away patches of new vessels before they cause problems.
Another consequence of diabetes for the eye is cataracts. Diabetics are far more likely than average to develop cataracts at a younger age. Fortunately these are easy to treat.
The best way to prevent all of these symptoms is good sugar control, good blood pressure control and a healthy diet. On the horizon are now genetic manipulations which can turn other cells in the body into insulin producing cells to replace the function of those lost to the disease, and it may also be feasible to use stem cell techniques to derive new insulin secreting cells which can be transplanted into affected individuals to boost insulin production. That this might work are the results from Canada using pancreatic cell transplants from cadaveric donors which have shown initial promise in small groups of patients.
TNS
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Thanks, that was really helpful ^_^
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Impressive!!! The Naked Scientist, how long did it take you to type all that out? It is some amazing contribution.
Tom
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Thanks. It only took about 10 minutes because it was from memory rather than from references.
TNS