If you are diabetic dog has sebaceous warts on it, those are excellent places to get blood samples for glucose testing at home. There are no nerves in a sebaceous wart because they are made of purely sebaceous gland tissue and not the nerves that go with that. The blood in a sebaceous wart is a little bit older than the blood in the rest of the system so the sugar is going to be off by possibly 15 points. But when you are trying to tell the difference between 60 and 600, it doesn’t matter.