PATHOPHYSIOLOGY OF SECONDARY COMPLICATIONS OF DIABETES MELLITUS
Diabetes mellitus (DM) is the most common endocrine metabolic disorder, characterised by hyperglycemia. The cause of this hyperglycemia is either insufficient or inefficient insulin which leads to the imbalance in the metabolism of not only carbohydrates but also protein and lipids. Diabetes mellitus is associated with various kind of abnormalities which affects almost all the parts of the body including eye, kidney, brain, foot etc. Hyperglycemia is not the only reason which gives diabetes mellitus a tag of most apocalyptic disease; it is the complications which arise from the higher concentration of glucose or metabolites comes from its variant metabolic pathways. DM causes both microvascular and macrovascular complications. Microvascular complications, caused by the damage of small blood vessels, includes nephropathy (kidney disease), retinopathy (eye damage) and neuropathy (nerve damage) whereas macrovascular complication, caused by the damage of large blood vessels, includes blood vessels arteries and veins. There are six metabolic pathways are there which normally leads to these complications. These pathways are sorbitol pathway, advanced glycation pathway, Hexosamine pathway, PKC pathway, ketoaldehyde pathway and oxidative stress.
Table 3: Long-term complications of diabetes caused because of hyperglycemia (reference)
Long-term complications of diabetes
Tissue or organ affected What happens Complications
Blood vessels Fatty material builds up and blocks large or medium-sized
arteries in the heart, brain, legs, and penis. The walls of
small blood vessels are damaged, and they do not transfer
oxygen to tissues
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Poor circulation causes wounds to heal poorly and can
lead to heart disorders, strokes, gangrene of the feet
and hands, erectile dysfunction, and infections
Eyes The small blood vessels of the retina are damaged Decreased vision and ultimately, blindness occur
Kidneys Blood vessels in the kidney thicken. Protein leaks into urine Kidneys malfunction and ultimately kidney failure occur
Nerves Nerves are damaged because glucose is not metabolized
normally and the blood supply is inadequate
Legs gradually weaken. People have reduced sensation,
tingling, and pain in their hands and feet
The nerves that control blood pressure and digestive
processes are damaged
Skin Blood flow to the skin is reduced, and sensation is
decreased resulting in repeated injury
Swings in blood pressure occur. Digestive function is
altered; Erectile dysfunction develops. Swallowing
Sores and deep infections (diabetic ulcers) develop.
Healing is poor
Blood White blood cell function is impaired People become more susceptible to infections
(urinary tract and skin)
Connective tissue Glucose is not metabolized causing tissues to thicken
Carpal tunnel syndrome and Dupuytrenâ€™s contracture
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