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Tasting urine was an integral part of the medical art, above all because there were no other methods to analyze it, and diabetes was a rare case in which the practice proved useful in making a diagnosis because the urine was abundant and above all sweet. The first to establish a distinction between diabetes “mellitus,” where the urine is as sweet as honey, and the other forms (“potius salsus quam dulcis”) was the Englishman Thomas Willis (1621–1675) in his Pharmaceutice Rationalis sive Diatriba de Medicamentorum Operationibus in Humano Corpore of 1676 (Fig. 8) [17].

Fig. 8. Frontispiece and passage “De Diuresi nimia, eiusque remedio, and speciatim de Diabete …” from Thomas Willis Pharmaceutice Rationalis sive Diatriba de Medicamentorum Operationibus in Humano Corpore. London, 1676. The Museum of Diabetes, Turin. www.museodeldiabete.it. Reprinted with kind permission.

Subsequently, by letting the urine evaporate and challenging the residue with yeast, Matthew Dobson (1732–1784) demonstrated in 1776 that the sweet taste was due to the presence of sugars capable of fermentation [18]. Incidentally, already in the first half of the 500s, Paracelsus had boiled to evaporation the urine of diabetic patients obtaining “salt” as residue. Although he did not recognize this as sugar, he had claimed that thirst and diabetes were always due to the accumulation of such “salt” in the blood.

The first to take advantage of Matthew Dobson’s observations on the presence of sugar in the urine, and apply it to monitor the results of treatment, was John Rollo (ca. 1750–1809). Surgeon-General of the Royal Artillery, Rollo should also be credited for giving the first clear directions to limit carbohydrates in the diet, although for the wrong reason. Convinced that the cause of diabetes was “a primary and peculiar affection” of the stomach in which some morbid change in “the natural powers of digestion and assimilation” led to the formation of sugary material in the organ, mostly from vegetable matter, he recommended a diet rich in old meat and fat [19, 20]. In his Notes of a Diabetic Case of 1797, followed a year later by An Account of Two Cases of the Diabetes Mellitus, Rollo reported on the diet inflicted on his first patient, a fellow army officer and personal friend (Fig. 9). On October 19, 1796, Captain Meredith was started on a definitely unpalatable regimen:

Fig. 9. Frontispiece and first two pages of John Rollo’s Traité du Diabète Sucré. French translation. Paris, 1798. Reprinted with kind permission.

“… The diet to consist of animal food principally and to be thus regulated:

Breakfast. One and a half pints of milk and half a pint of lime-water, mixed together; and bread and butter.

Noon. Plain blood puddings, made of blood and suet only.

Dinner. Game, or old meats, which have been long kept; and as far as the stomach may bear, fat and rancid old meats, as pork. To eat in moderation.

Supper. The same as breakfast.”

Meredith was militarily abiding, and did improve. Others, including a general, were not so lenient. Rollo, a Scotsman, published mostly on matters of military medicine and also in support of Edward Jenner’s vaccination (Medical Report on Cases of Inoculation, 1804).

Finally, in 1815, the French chemist Michel-Eugène Chevreul (1786–1889) identified the sugar as glucose, opening the road to its quantitation for diagnostic and therapeutic purposes [21]. The solution was developed by the Germans Carl August Trommer in 1841 and, with better luck, in 1848 by Hermann Christian von Fehling (1811–1885) [22], who developed the method used to measure glycosuria almost to the present day. These developments were not universally acknowledged, anyway, and leveraging upon rare cases of renal diabetes and other non-diabetic “melliturias,” detractors fought fierce diatribes which endured well into the first half of the 20th century.