Like "Well, the fact that you can't spell diabetes doesn't really fill me with confidence that you know anything about it. Plus you say that too high a sugar level or too low a sugar level are symptoms but then say that diabetes is "impaired carbohydrate, protein, and fat metabolism owing to insufficient secretion of insulin or to target tissue insulin resistance" which is essentially saying the same thing because they are symptoms as well. It would be nice to have a one sentence answer to what diabetes is but I don't think you will ever find one since even in people with the same type of diagnosed diabetes the manifestation is different in each person. It's largely genetic, there are environmental factors which are still unknown but the underlying cause and mechanism of action is still not understood. I don't know how much man made contribution is involved but looking at it just from the gene pool, since diabetics have had better and better treatment over the decades and are living longer and longer the diabetes genes are spreading a lot more than they would have decades ago. Who really knows though, I don't, experts don't and I'm sure no one else does yet. However, if you have found the underlying truth to diabetes I expect we'll be hearing a lot about it very soon through multiple channels and you will be receiving a nobel prize next time since it's a pretty huge and medically significant discovery."