OTHER CHARACTERISTICS OF DIABETIC URINE.
1. Quantity of the Urine ; Specific Gravity.—Polyuria is one of the most striking symptoms of diabetes. It often causes the patient uneasiness before any other phenomena of the disease are noticed. The desire to urinate often wakes the patient and forces him to get up, although as a general rule, if not always, the quantity of urine secreted during the night is less than that secreted during the clay time. This is worthy of note, since in other sufferers from a patho logically increased diuresis it frequently happens that from two-thirds to three-quarters of the entire amount of the urine is secreted during the night (Quincke).
The total volume of urine secreted in the twenty-four hours amounts in many cases to 10 litres (17+ pints) or more—sometimes even 15 or 20 litres ! In cases of moderate severity, where there has been uo regulation of the diet, the average quantity secreted is from 4 to 6 litres (7 to 10+ pints).
An increase in the amount of sugar brings an increase in the amount of urine; but ordinarily the amount of urine rises less rap idly than does that of sugar, so that when the volume of water is greater the percentage of sugar is increased. The specific gravity is consequently higher the greater the amount of urine secreted—a phenomenon that is not observed in any other disease. The follow ing tabular view, made up from a large number of urinary tables, shows the specific gravity and percentage of sugar corresponding to given amounts of daily excretion of urine. It must be remembered, however, that individual cases frequently present exceptions to the averages here given: The relation of the amount of sugar excreted to the total volume of the urine is shown very clearly when the patient is transferred from a mixed diet to one consisting of meat and fat; the quantity of urine immediately falls and along with it that of the sugar, although never in exactly the same ratio. This is shown in the following table from E. Cless: Total amount Specific Percentage of urine. Gravity, of sugar.
Mixed diet (daily average of four days) 6,360 c. c. 1,038 7.05 Animal diet (daily average of seven days) 3,800 c.c. 1.031 2.2 If, under the influence of a strictly meat diet, the urine becomes entirely or nearly free from sugar, then its daily secretion approaches the normal amount. But the specific gravity remains higher, be cause the urine is rich in the end products of the meat ingested.
There are many exceptions to the rules above given. Some may be formulated, others defy any schematic representation.
u. The glycosuria is often preceded for a rather long period by greatly increased diuresis; the urine in this case is of low specific gravity and resembles that in diabetes insipidus, but it is better to call it premonitory polyuria than diabetes iusipidus, for in the pres ent state of our knowledge everything points to the latter as being a disease yene•is and having nothing to do with diabetes mellitus. It is very interesting to note that many authors have observed only polyuria after experimental injury to the pancreas, and not glyco suria; if diabetes mellitus did not ensue the polyuria rapidly disap peared.
b. When a cure of diabetes mellitus takes place, there often follows a period, extending over weeks or months, of polyuria without glycosuria. In many of these cases the explanation lies in the fact that the patients have acquired a habit of drinking large quantities of water which they cannot easily abandon. If the amount of water is lessened under the physician's orders, extreme thirst is felt for a number of days, but this gradually subsides and a normal diuresis is established. In other cases the thirst cannot be overcome, and the patients lose their appetite, sleep poorly, and feel depressed when ever the attempt is made to reduce the polyuria by restricting the allowance of water.
c. There are some rare cases of diabetes mellitus in which, despite a large percentage of sugar, only a normal quantity of urine is se creted, and the demand of the organism for water does not exceed physiological limits. The causes for this unusual condition are not known. Peter Frank first described these cases a hundred years ago, naming the condition " diabetes decipiens." d. The natural ratio between diuresis and glycosuria may be dis turbed artificially in various ways. A diminution in the amount of urine through reduction in the quantity of water can seldom be brought about, as experience has shown that diabetics bear this very poorly, and if it is insisted upon simply disobey. On the other hand the reverse often obtains. In patients undergoing a " drink cure" the urine is naturally largely diluted; it increases in amount while the specific gravity falls and the percentage of sugar is propor tionately reduced.