Not automatically. In many student travel policies, cover is built mainly for unforeseen events, accidents, and sudden serious illness, not for previously known or ongoing medical conditions unless the relevant rules are satisfied.
The danger here is assuming that a stable condition is always ignored or that any illness count as “new”. Policy wording normally gives much more precise rules than that. If the condition existed before issue or had required treatment beforehand, extra care is needed when assessing whether cover is likely.
If your question relates to a real health history, use support carefully and be precise about dates and treatment history.