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

Here is Why You Need An Adapter

The outlet and plug type used in French Guiana are C, D and E and in Saint Kitts and Nevis are D and G. This is how they look like.

Saint Kitts and Nevis

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

Type D

Type G

French Guiana

In French Guiana, outlets of type C, D and E are in use.

Type C

Type D

Type E