Why do diabetic people take so long to recover after surgery?

Impaired healing. Diabetics generally heal more slowly due to a combination of high blood sugar slowing down the cells the body uses to heal and because they often have decreased circulation particularly in small blood vessels. If you are diabetic and planning to have surgery, it is importan to get with your doctor and work to get your blood sugars under tight control both before and after surgery.
Diabetes. Diabetes affects small blood vessels. After surgery, healing is impaired due to decreased blood flow in the tiny blood vessels.