Agreed with the above. Not declaring he has diabetes is a very risky move and a bad idea. If he has any sort of issues that ends up in an insurance claim, you can expect the insurer to deny the reimbursement because you failed to declare a pre-existing condition. In other words, lying in the application will likely invalidate your entire policy. You should be 100% truthful. The last thing you want to do is lie, have him come to Canada and end up needing hospitalization and then end up with a hospital bill for tens of thousands of dollars (or more) that you have to pay because your insurer refuses to.
There is no chance your father would be able to claim he doesn't know he has diabetes.
Failure to disclose diabetes as a pre-existing condition could render your dad's insurance contract voidable by the insurer. So, your dad won't have super visa insurance if he makes an insurance claim.
