I'm prompted by this inscription that Laura de Force Gordon put in a time capsule in San Francisco in 1879:
"If this little book should see the light after its 100 years of entombment, I would like its readers to know that the author was a lover of her own sex and devoted the best years of her life in striving for the political equality and social and moral elevation of women."
But are there any diaries by queer, closeted people that survive from Medieval or Renaissance times?
Yes, there is quite a bit of primary source documents from mostly male closeted homosexuals. Many were poets who wrote down love poems about other men or boys. In a poem written by Hildebert of Lavardian ,the author mentions the Greek mythological figure Ganymede, often seen as the most common image in medieval homoerotic poetry. By the beginning of the 13th century, Ganymede "the androgynous and somewhat wanton boy" became a symbol for homosexual love.
Another medieval poet, Baudri, writes "God made our natures full of love...What we are is a crime, if it is a crime to love,/ For God who made me live made me love."
Both sources are from Homophobia- A History by Byrne Fone
Hope that helped answer your question