In 1872, German Egyptologist Georg Ebers discovered Ancient Egyptian medical records, of which some date back to around 3400 BCE. One in particular mentions the cure for excessive urination (a symptom of untreated Type 1 Diabetes) was "A measuring glass filled with Water from the Bird pond, Elderberry, Fibres of the asit plant, Fresh Milk, Beer-Swill, Flower of the Cucumber, and Green Dates." Of course, this didn't work, but it's significance is that the Ancient Egyptians recognized a key symptom in diabetes mellitus and attempted to treat it. In around the 1st Century BCE, Aretaeus, the Greek Physician, first coined the term "diabetes," and described its symptoms (excessive urination and starvation) as "the melting down of the flesh and limbs into urine." Ancient Hindus also noted the attraction of insects like flies and ants (a product of excessive sugar in the urine) and noted that those affected by diabetes had "honey urine." Insulin wouldn't be discovered and isolated until 1922-- it was a death sentence before then.

I'm a T1 diabetic myself, so I thought this history was pretty interesting.

Source: http://spectrum.diabetesjournals.org/content/15/1/56.long