Abstract
A technically simple and rapid procedure for the determination of the blood sugar which gives results which are little, if at all, affected by the non-sugar reducing substances of the corpuscles and plasma is presented. The problem of non-sugar reducing substances has been approached in 2 ways—by using copper solutions which are effective on the glucose of the blood only (Folin, S. R. Benedict) and by obtaining protein-free filtrates from which the non-sugar reducing substances are removed along with the protein (Somogyi). The second procedure is obviously the more practical, and is attained in our methods by increasing the proportion of tung-state and sulfuric acid in relation to the volume of blood precipitated.
Dr. J. S. Boyd (1923), working in this laboratory, adapted the Folin-Wu method for finger-tip blood specimens to meet the increase in the number of blood-sugar determinations necessitated by insulin control of diabetics. We are now doing over 4200 blood sugar determinations yearly in the routine diabetic service alone. The procedure may be used for venous specimens as well. About 2.5 times the amounts of sodium tungstate and sulfuric acid over that in the original Folin-Wu procedure in proportion to the volume of blood taken were used as the precipitant. As completely glycolized specimens of blood give no color with Boyd's method, Shrader 1 added increasing amounts of glucose to blood after glycolysis and determined these. Calculated values for the glucose found over a range of 70 to 140 mgm. percent corresponded closely to the amounts of sugar added, with progressively increasing variation above and below these figures.
Shrader prepared a table for the glucose in mgm. percent corresponding to colorimetric readings (in mm.) over the ordinary clinical range of blood sugar values from a graph constructed from his data.
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