MSD Manual

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Complications of Diabetes

Complications of Diabetes

Tissue or Organ Affected



Blood vessels

The walls of small blood vessels are damaged so that the vessels do not transfer oxygen to tissues normally, and the vessels may leak.


The small blood vessels of the retina are damaged, leading to formation of new fragile blood vessels that tend to bleed.

Vision decreases, and ultimately, blindness occurs.


The small blood vessels in the kidneys thicken.

Protein leaks into urine.

Blood is not filtered normally.


Abnormal fat deposits collect in the liver.

Peripheral nerves

Nerves are damaged because glucose is not used normally and because the blood supply is inadequate.

Legs suddenly or gradually weaken.

People have reduced sensation, tingling, and pain in their hands and feet.

The nerves that control internal body processes such as blood pressure and digestion are damaged.

Swings in blood pressure occur, and blood pressure can fall when the person stands.

Swallowing becomes difficult.

Digestive function is altered, and sometimes nausea or bouts of diarrhea occur.


Blood flow to the skin is reduced, and sensation is decreased, resulting in repeated injury.

Sores and deep infections (diabetic ulcers) develop.

Healing is poor.


White blood cell function is impaired.

Connective tissue

Glucose is not used normally, causing tissues to thicken or contract.