Just because you're diabetic, doesn't mean you can't wear contact lenses. However, it's important that you're aware that in the event of an injury (e.g. a corneal abrasion) it might take longer for your eyes to heal and any infections might take longer to clear than a contact lens wearer who doesn't have diabetes.

Therefore excellent hygiene and handling are all the more important and your optician will probably advise that you are fitted with contact lenses that have good oxygen transmission properties. It's best to speak to your local GP or optician, who should be able to answer all your questions.