You Do Need power plug adapter while traveling from Guatemala to Saint Kitts and Nevis.

Here is Why You Need An Adapter

The outlet and plug type used in Saint Kitts and Nevis are D and G and in Guatemala are A and B. This is how they look like.

Guatemala

In Guatemala, outlets of type A and B are in use.

Type A

Type B

Saint Kitts and Nevis

In Saint Kitts and Nevis, outlets of type D and G are in use.

Type D

Type G