Type 1 diabetes makes up about 10% of the diabetes cases in the United States .  Most cases of type 1 diabetes are diagnosed in those under the age of 30.  Symptoms often develop abruptly and the diagnosis is often made in an emergency room setting.  The patient may be seriously ill, even comatose, with very high glucose levels and high levels of ketones (byproducts using fat as an energy source).  Type 1 diabetics make very little or no insulin.  Any insulin producing beta cells they do have at the time of diagnosis are usually completely destroyed within 5 to 10 years leaving them entirely reliant on insulin injections to live.  The exact cause of type 1 diabetes is unknown, but a family history of diabetes, viruses that injure the pancreas and autoimmune processes (where the body's own immune system destroys the beta cells) are all thought to play a role.  Type 1 diabetics may have more severe medical complications, sooner than other diabetics.  For instance, about 40% of those with type 1 diabetes will develop serious kidney problems leading to kidney failure by the age of 50.