Signs and symptoms of type 1 and type 2 diabetes can include increased thirst and urination, increased appetite, loss of weight, fatigue, change in vision, frequent infection, and patches of darkened skin.

Type 2 diabetes occurs when a person has blood glucose (sugar) levels that are higher than normal and their body does not use insulin properly. Causes include genetics and environment and can also include being overweight, but not all patients with type 2 diabetes are overweight.

Source:

http://www.mayoclinic.org