When you have a health issue or a disability, the question is reasonable accommodation. I am not sure what all is involved in working offshore, or how serious your diabetes is, but they may be concerned that there is not adequate time/facilities to provide medical attention in an emergency. I would think that would be an issue for clearance by your doctor. You may want to meet with an employment law attorney to see if your case meets all the elements required for you to be able to pursue a claim.
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