Benedict's reagent is a chemical compound made up of copper sulfate, which can detect the presence of glucose or fructose. A reagent is a chemical that is applied to another substance in order to produce a chemical reaction that can give valuable information regarding the substance. Benedict's reagent is most commonly used to calculate ways of reducing glucose or fructose in foods. In the past, it was the way diabetes was detected through the testing of urine..

In food tests, a small amount of the food is added to Benedict's reagent and boiled for several minutes to test the amount of sugar present. The results will show precipitates, or solid formations within the tested substance. The amount to which a precipitate is present can show the exact glucose or fructose present in the substance.

Since the precipitates are likely to be very small, Benedict's reagent also shows color changes that can gauge the amounts of the sugars glucose and fructose. For example, a substance treated with Benedict's reagent that is green shows very little or possibly no glucose or fructose present. On the other hand a red color indicates a high quantity of these sugars.

In people who are suspected of having diabetes, analysis of urine is one of the main diagnostic method. Pregnant women used to undergo an analysis of urine that was treated with Benedict's reagent to check for gestational diabetes. Today, other tests may be used because they are more precise in measuring sugar levels.

Pregnant women may resent these frequent urine tests but they are in fact very important to rule out diabetic conditions during a pregnancy. Benedict’s reagent only works so far in diabetic testing however, since presence of fructose in the urine does not suggest a diabetic condition.

Thus, urine must be further tested, if it shows positive when mixed with Benedict's reagent to evaluate for the presence of glucose. For some, this may mean no further testing with Benedict's reagent, but drinking a glucose solution that most find quite distasteful. However, untreated diabetes should not go unchecked. Thus, diagnosis is extremely valuable and may help begin early treatment, which can significantly change later outcome.