You could try the clothespin trick. If that doesn't work, and the carrier-type restraint is not an option or doesn't work, then I would try approaching this very gradually. Since he isn't getting insulin, there is no big hurry to get the test, so I would try desensitizing him slowly to having his ears (or paw) handled. Start out just having him lay next to you or wherever you want to test him, and pet and talk to him, then handle his ear or paw for a few seconds...try to avoid pushing it to the point of him resisting, then immediately give a treat. Gradually increase the time, then start bringing the meter and lancet pen with you, but don't use it, then hold it up to his ear without triggering....you get the idea, right?
Some cats HATE to be restrained, and will fight like crazy against it. Tinkles is like that, I never really restrained him to test him...DH held him sometimes in the beginning, but I deliberately took my time and avoided heavy restraint because I knew it would only backfire. I would back off a little when he resisted, and try again after he settled down....try making it pleasant, and take baby steps...it worked well for us.