The Truth About Stacey by Ann M. Martin

A new girl adjusts to life in a small town while juggling school, friendships, and babysitting responsibilities, all while hiding that she has diabetes; afraid of being treated differently, she keeps her condition a secret, which creates stress and misunderstandings until she finds the courage to be honest and accept the support of her friends, learning to manage her illness without giving up who she is.

Purchase from Bookshop.org