\documentclass{article}

\usepackage[ngerman]{babel}
\usepackage{glossaries}

\GlsSetQuote{+}% requires glossaries v4.24

\makeglossaries

\newglossaryentry{Uberlingen}{name={{\"U}berlingen},
  sort={"Uberlingen},
  description={a place}}

\begin{document}

\gls{Uberlingen}

\printglossaries
\end{document}
