Diabetes is usually not difficult to recognize. Clinical symptoms include frequent urination, excessive thirst or hunger, and either accelerated weight loss or weight gain. Fatigue, vision changes, and mood changes can also be associated with it, and the disease may lead to poor wound healing.

The word “diabetes” (originally called “diabetes mellitus”) is derived from the Greek word “diabetes,” which means “to siphon,” and the Latin word “mellitus,” which signifies “sweet.” The disease was first defined in the 17th century by the sweet taste of sufferers’ urine.

However, earlier cultures — including the Greeks, Chinese, Egyptians, and Persians — had identified sweet-tasting urine among people with such an illness. In those ancient times, physicians could diagnose diabetes from excess sugar in the urine, but they had no idea how to treat it.

In 1889, physicians explained that dogs that had their pancreas removed developed symptoms of diabetes and died shortly thereafter.

The pancreas is a gland in the stomach that is responsible for producing insulin, which is crucial for transmission of sugar from the blood into cells. Not surprisingly, without a pancreas, an insufficient amount of insulin is produced, and diabetes — that is, excessive blood sugar — can develop.

In 1921, other physicians found that dogs that developed diabetes through having their pancreas removed could have symptoms reversed by being treated with an extract from the pancreas — what is now known as insulin.

In 1922, the first human diabetic was successfully treated with insulin.