It actually sounds like Hyperosmolar hyperglycemic nonketotic coma (HHNC) to me. It has a mean age of onset early in the seventh decade of life, and Residents of nursing facilities who are elderly and demented are at the highest risk.
In terms of pathophysiology: Dr's Sagarin & McAfee explain it the best:
Unlike patients with DKA, patients with HHNC do not develop ketoacidosis, but the reason for this is not known. Contributing factors include the limitation on ketogenesis by hyperosmolarity, the lower levels of free fatty acids available for ketogenesis, the availability of insulin in amounts sufficient to inhibit ketogenesis but not sufficient to prevent hyperglycemia. Preceding or intercurrent illness is common, but the underlying cause may be difficult to ascertain. Pneumonia and urinary tract infections (UTIs) are the most common underlying causes of HHNC.
No comment as to what I would have done....
There is a fascinating article on the subject at:
Hope this helps!