Sadek was formerly part of the German Empire. In the German Empire, the place was called Sadok.
The place is now called Sadek and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Sadok | Russian Empire | Sejny | 1914 |
| Sadek | Poland | Sejny | 1921 |
| Sadok | German Empire | Sudauen | 1939 |
| NN | Poland | Suwałki | 1945 |
| Sadek | Poland | Suwałki | 1992 |