A study, published in the online journal "Nature" found that a blind cave fish, Mexican Tetra (Astyanax Mexicanus), is insulin resistant. 

For humans, insulin is produced by the body to turn glucose into energy for daily activities. In people with type two diabetes, the body is either not making enough insulin or the insulin isn’t working correctly, which results in high blood sugar.

The Mexican Tetra, on the other hand, also experience heightened blood sugar, but surprisingly they don't experience the negative effects that humans do.

The researchers found that the fish are always insulin resistant so their bodies can actually store the glucose as fat for when there is not enough food around.

By studying the fish and understanding how they are able to live healthy lives despite having an insatiable appetite and high blood-sugar, researchers think we can make the life of people with type two diabetes a lot more manageable.