Revision of a method for the determination of high blood glucose values, based on the Hagedorn and Jensen technique.

An extension of the Hagedorn-Jensen method for handling blood samples with high glucose values is criticized. This modification, which is frequently used—at least in The Netherlands—consists of the addition of a second quantity of ferricyanide reagent to the test, after one has observed, by the decolorization of the fluid, that the first quantity was too small. It is shown that current descriptions of this procedure are insufficiently detailed, as they do not give the exact time for the second addition. If one does not give attention to this point, the results found may be grossly incorrect (up to 30% for a real value of 1000 mg/100 ml). Blood glucose values of diabetic patients in coma, formerly obtained by this method, must be regarded therefore with suspicion. While retaining the essentials of the method, several improvements are suggested.