\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}
