I assume that both your current job and your new job offer you health insurance. If there is a waiting poeriod before the new job health insurance kicks in you can use COBRA coverage from your old job to cover the period. If the new job is with a small employer then your health could affect thier insurance perimums when thier insurance company finds out about it so they might be more interested.
That aside or if insurabce is not an issue then I would say go for it. You do not have to tell them about your diagnisis unless they ask. I would not lie about it if they do but there are likely restrictions on what they can ask that a Lawyer can explain better than I can so see a lawyer if it will set your mind at ease. I have changed jobs twice with my same employer twice sionce my diagnosis and have always bee up front about my situation but I have never looked for new outside employment so my experience is not the same. Good Luck