Dobson's experiments on diabetic urine

Peter Dickonson, a 33-year-old former soldier, was admitted to the public hospital in Liverpool on 22 October 1772, passing 28 pints of urine every 24 hours. He was emaciated, his thirst could not be quenched, and his skin had become dry and hard like rough parchment. Matthew Dobson, a physician there, had by then seen nine people with diabetes, and in every one the urine had been sweet to some degree. Other authors denied that it was sweet at all.

Dobson set some of the urine aside in an open vessel. It fermented, giving off a smell like wine, then soured to vinegar and finally turned putrid. Eight ounces of blood from the patient's arm separated into a serum that looked like cheese whey and tasted sweetish, though less sweet than the urine. Two quarts of urine were then evaporated to dryness over gentle heat, watched by Mr Poole, the hospital apothecary, and Mr Walthall, a house apprentice. What remained was a granulated white cake weighing a little over four ounces. It smelled like brown sugar and by taste could hardly be told from sugar.

Because the serum was sweet, Dobson concluded that the sugar was not made in the kidneys but was already present in the blood. He treated diabetes as a disorder of digestion and assimilation affecting the whole body. His paper, signed at Liverpool on 20 November 1774, was printed in 1776 in the fifth volume of Medical Observations and Inquiries. About a century earlier, in 1674, Thomas Willis had written that diabetic urine was wonderfully sweet, like sugar or honey.

Dickonson stayed in hospital for seven months, and for a time he improved to 14 pints a day on remedies that included bark, rhubarb, alum whey and lime water. At the end of May 1773 Dobson paid for him to travel to Matlock to drink the waters. He never went, and Dobson never learned what became of him.