Will my pre-existing condition coverage break when I change insurers in the UAE?

Your concern is valid, and the fix is mostly about sequencing. When you join a new insurer, their underwriters can treat you as a fresh member and apply waiting periods to pre-existing conditions — unless you prove continuity of cover. The document that does this is a certificate of continuity (COC) from your current insurer, confirming your coverage dates without a break. With it, your thyroid condition should be carried over as already covered rather than re-underwritten from zero. Do these things before your current policy ends: request the COC from your existing insurer in writing now, while you are still their member and the request is routine; make sure there is no gap between the old policy's cancellation and the new policy's start date, since a gap is the main thing that genuinely breaks continuity; give the COC to the new insurer or your new employer's broker during onboarding, not after; and ask the new insurer to confirm in writing that pre-existing condition cover continues without fresh waiting periods. Keep copies of everything, including proof you disclosed the condition. If the new insurer later disputes cover for medication you disclosed and documented, a lawyer can review the policy terms and challenge the refusal.