| 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. | |
| 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. |
| White blood cell function is impaired. | |
| Glucose is not used normally, causing tissues to thicken or contract. | |