How was blood sugar tested before meters?

How was blood sugar tested before meters?

Before the invention of blood glucose meters, blood sugar levels were tested using various methods that were more complex and time-consuming. Here are a few historical methods used to measure blood sugar before the introduction of meters:

Benedict's Test:

This qualitative test, developed in 1908 by Stanley Ross Benedict, was used to detect the presence of glucose in urine samples. It involved adding Benedict's reagent (a mixture of copper sulfate, potassium thiocyanate, and sodium carbonate) to urine. The presence of glucose in the urine would cause the solution to change color. The intensity of the color change indicated the approximate concentration of glucose.

Fehling's Test:

Similar to Benedict's test, Fehling's test, developed in the 1840s by German chemist Hermann von Fehling, was also used to detect glucose in urine. It involved adding Fehling's reagent (a mixture of copper sulfate and potassium hydroxide) to urine. If glucose was present, it would react with the copper ions and form a brick-red precipitate of cuprous oxide.

Hagedorn-Jensen Method:

This quantitative method, developed by Hans Christian Hagedorn and Poul Aage Jensen in the 1920s, was used to measure blood glucose levels. It involved precipitating proteins from a blood sample using zinc sulfate and potassium ferrocyanide, then filtering the mixture and analyzing the filtrate for glucose content using a titration process with a standard potassium permanganate solution. The amount of permanganate required to oxidize the glucose in the filtrate would indicate the blood sugar level.

Somogyi-Nelson Method:

Another quantitative method, developed by Michael Somogyi and Nels Paul Nelson in the 1930s, also involved precipitating proteins from a blood sample. In this method, a copper sulfate solution was added to the filtrate to form a copper-glucose complex. The complex was then oxidized, and the amount of reduced copper was determined through titration with a solution containing sodium thiosulfate. The blood sugar level could be calculated based on the amount of thiosulfate required.

These historical methods required laboratory equipment, chemicals, and skilled technicians, making blood sugar testing a challenging and time-intensive task. The development of blood glucose meters using electrochemical sensors revolutionized blood sugar testing, making it easier, faster, and more accessible to individuals with diabetes.