In speaking of the causes of Diabetes we must ever remember that they act only in certain conditions of the body, and these conditions are unknown, and will probably ever remain so, until we see such causes act. There is therefore in all cases of Diabetes a something added to the body, not discoverable it is true, which makes causes, that would otherwise be inoperative, produce the disease in question.

Causes may be divided into predisposing and exciting.

I. Predisposing

Constitutional Predisposition

This has been disputed, but most authors are agreed in attributing much influence to this cause. The following consideration should have some weight in determining the question; there are three elementary principles which serve for the nutrition of the healthy body, Albuminoid, Fatty, and Saccharine or Amylaceous: from a defect of assimilation of the first we have gout or gravel: from a defect in the second we have fat deposited in various parts of the body: and from a defect in the third we have Glycosuria or Diabetes. As the first two are universally allowed to be constitutional or here-ditary, so I think ought also the third. Authors describe numbers of cases of Diabetes that appeared in the same family and amongst near relations. I have seen Diabetes in a brother and two sisters, and a cousin, and I think there can be no doubt of its being hereditary. I have been much struck in my patients with the number of their near relations who have been affected with diseases that are allowed to be hereditary; consumption and scrofulous diseases being especially prevalent: one patient, for instance, had a mother die of consumption, a sister of hydrocephalus, a brother from scrofulous knee-joint, another sister from malignant disease of the womb: in another family one brother and two sisters were affected with Diabetes and two or three died of malignant disease. I might say that in eighteen cases where the history was carefully ascertained all had some relations who had died of consumption, or had scrofulous or malignant diseases. M. Mialhe says he has observed the disease in three brothers; in two brothers of another family, and he has often seen a diabetic patient have a brother who was troubled with gravel.

Sex

In the 10 years from 1850 to 1860, 4564 deaths from Diabetes were registered in England and Wales: 3032 of these were males, 1514 females; the disease being about twice as common in males as in females. It is important to remark that the development and exercise of the sexual functions appear to increase the liability to diabetes in both sexes; and the diminished frequency of the disease in women after 45, as compared with men of the same age corresponds with the earlier de cline of the sexual activity in the female sex: the maximum mortality in males is between 45 and 55, in females between 25 and 35.

Age

Diabetes prevails among young and middle-aged men; the deaths being rare under 5 years of age. I have not seen a case under 8 years, but in the Register of deaths for 1861 9 under 5 years of age are entered, 5 males and 4 females: in 1867, 7 cases are registered, 4 males and 3 females. Dr. Prout has seen only one case in a child 5 years old, and only 12 between the ages of 8 and 20 out of a total number of 700. Dr. West, in the third edition of his work on the Diseases of Infancy and Childhood, 1854, says a case has never come under his notice, but in the fifth edition, 1865, he mentions two cases, one a girl 3 ½ years old and the other, her sister, 2½.

After 65, Diabetes is comparatively rare, judging from the number of deaths that then take place; the mortality is greatest between 25 and 25, and is tolerably uniform between these ages. In extreme old age death from Diabetes is very rare, not only absolutely but as to the mortality from all other causes.

Dr. Bence Jones however considers it more frequent. Of 29 patients 11 were over 60, and of these 6 were over 70. It must however be noted, according to M. Dechambre, that many old people have sugar in their urine which he says is due to imperfection of the colouring matter of the blood.

Occupation

Urban and manufacturing districts suffer more from Diabetes than rural; if we take London, Lancashire, and the West Riding of Yorkshire, as representing the former, we find the mortality from Diabetes as 2.5; 3.2; and 4.1 respectively, for every 100,000 inhabitants; whilst in Wales and the Southern Midland Counties, which are mostly agricultural, the respective numbers are 1.2 and 1.5 for the same number of inhabitants.*

Condition And Temperament

It is most frequently seen in those who appear to be strong and in good condition. In 100 cases in which this has been noticed 70 seemingly were strong.

* Roberts' Urinary Disease, p. 165.

Cowley and Willis considered that the lymphatic temperament predisposed to the disease. Nicolas and Gaudeville considered the muscular most prone. M. Jarda6 thinks the lymphatico-nervous the most liable. Of 72 cases I have collected, in which the temperament was men-tioned, the following is the relative frequency.

Season And Climate

The action of these two is undoubtedly alike, but they must have different results. Seasons have only a fleeting influence, climate produces deep modifications in the constitution. M. Contour in his treatise gives this short resume of our knowledge, "Diabetes is nowhere more common than in England and Holland. Dr. Willis says that his friend Dr. Babington informed him that, while he was preparing to pass an examination at Cambridge, his father who had an extensive practice shewed him 33 cases of this disease at one time. It is believed that the cold and damp climate is the sole cause of this frequency, but the manner of living of the inhabitants has perhaps a greater influence in the production of the disease than the constitution of the atmosphere; indeed, one sees that Diabetes becomes rarer in cold countries, and occurs more frequently in certain warm ones. Thus Sir Charles Lefevre says he examined the register of the principal Hospitals, civil and military, of the Russian Empire and did not find the mention of a single case. Sir James Wylie did not meet with a single example among more than two millions of soldiers whom, as Inspector General of the Russian army, he had examined. On the other hand, Diabetes is far from being rare in Portugal, Ceylon, St. Dominique, or Egypt; in the latter country the Arabian, Rable Moyses, has seen 20 cases in 10 years and adds "Quod multoties generatur (Diabetes) in regionibus calidis et forte accidit in regione Ægypti saporitate aquae Nili quam omnes bibunt." P. Frank has met with this disease more frequently in Italy than in Germany; "during20 years'" says he, "in which I have practised among the different people of Germany I have seen only 3 cases of this disease; in Italy in the short space of 8 years I have met with 7 cases." In France, Diabetes is common enough. M. Rayer has seen more than 30 cases. "Some particulars which I have collected," says M. Contour, "lead to the belief that Diabetes is more common in Normandy:" this opinion was put forth by Nicolas and Gaudeville who attributed the frequency to the food of the inhabitants and especially to the use of fermented drinks, as for example cider, which is the common beverage."*