Diabetes can cause wounds to heal more slowly due to a number of factors, including:
Poor circulation
High blood sugar levels can thicken and narrow blood vessels, making it harder for blood to reach wounds and deliver oxygen and nutrients. This is especially common in the lower limbs, which are further from the heart.
Microvascular disease
Diabetes can cause microvascular disease that impairs blood flow and can lead to poor wound perfusion.
Hyperglycemia
High blood sugar can also lead to osmotic diuresis, which can decrease oxygenation and perfusion. Hyperglycemia can also increase the risk of wound infection, which can decrease healing.
Weakened immune system
High blood sugar can stress the body and make the immune system work harder, including white blood cells. Diabetic patients also have slower moving white blood cells than the average person, which can lead to a reduced immune response.
Peripheral neuropathy
This condition can reduce feeling in the feet, making it difficult to feel cuts or injuries that can lead to blisters or sores.