Hook into you response generator or create a middleware that does the following:
res.headersetHeader("Content-Type", "application/json; charset=utf-8");
Otherwise the browser displays the content in hisit's favorite encoding.
If this doesn't help you DB is probably in the wrong encoding.
Edit:For older node.js versions Since the answer is nearly 5 years old, the API has changed. For current node.js versions use:
res.setHeaderheader("Content-Type", "application/json; charset=utf-8");