Test For Presence of Sugar in Urine

Among the multitude of volatile and non-volatile waste substances produced in human and animal bodies, urine is by far the most significant by-product. Produced and excreted by means of the kidney and urethra, urine is the primary form of excreting water-soluble wastes from our bodies.

Urine has a light-yellowish colour thanks to the presence of a pigment called urochrome. It has a pH level which varies between 4.6-8 and is a complex aqueous solution of inorganic and organic matter. Besides, normal urine constituents such as urea, oxalic acid and lactic acid, sugar and blood may also be detected in case of an abnormal condition. Thus two general tests are performed to detect the presence of glucose in urine, which may be an indication of diabetes mellitus.

A urine sugar test helps detect levels of glucose that exceed the usual levels of 160-180 mg/dl. In the event of such an anomaly, the patient is diagnosed with a condition called glucosuria. 

Let us Now Learn More About the Urine Sugar Test Procedure.

Aim

To perform a test to detect the presence or absence of sugar/glucose in a sample of urine.

Theory

The following are the important properties of urine:

  1. Urine has a light-yellowish colour, imparted by urochrome.

  2. The pH of urine lies between 4.6-8.

  3. Organic compounds like urea, creatinine and uric acid are generally found in urine.

  4. Some inorganic compounds present in urine are sulphates, phosphates, sodium chloride and potassium chloride.

  5. In abnormal conditions, there may also be a sugar trace in urine, in addition to proteins, ketone bodies, blood and bile.

  6. In case glucose is detected in blood, the patient may have a condition called diabetes mellitus.

The urine glucose test performed to detect sugar presence in urine can be done using the following two methods.

  1. Benedict’s Test

  2. Fehling’s Test

Benedict’s test employs Benedict’s solution as a reagent. It is a mixture of sodium citrate, copper sulphate pentahydrate (CuSO4.5H2O) and sodium carbonate. On the other hand, Fehling’s test employs two reagents. These are:

  1. Fehling's Solution A: An aqueous blue solution of copper sulphate.

  2. Fehling's Solution B: An aqueous and colourless solution of sodium potassium tartrate.

When a sample of urine is boiled with these reagents, the glucose present in the sample reduces the copper sulphate in Fehling’s solution and Benedict’s solution. This changes the colour of the solution. Depending on the levels of glucose in the solution, the colours vary from brick-red, green to yellow precipitates.

The Following Table Helps illustrate the Urine Sugar Test Colour.

Percentage of Sugar Levels

Colour of Precipitate

No Sugar

Blue

0.5% to 1%

Green

1% to 2%

Yellow

2% and higher

Brick-red


Pop Quiz 1

  1. Which of these is a standard component of urine?

  1. Ketone bodies

  2. Creatinine

  3. Proteins

  4. Blood

Benedict’s Test

Materials Required:

  • Reagent (Benedict’s Solution)

  • A test tube

  • A test tube holder

  • Measuring cylinders

  • A sample of urine

  • Burner

Procedure

  1. Take a sample of urine with the help of a measuring cylinder (2 ml).

  2. Pour the sample into a test tube.

  3. Pour 5 ml of Benedict’s solution into the test tube containing the urine sample.

  4. Securely hold the test tube and heat it on the burner for two minutes.

  5. Keep stirring the tube.

Conclusion and Observation

Gradually, as the sample is heated, a yellow precipitate starts to form in the test tube. This indicates the presence of sugar or glucose in the given sample. 

Fehling’s Test

Material

  • Fehling’s Solution A and B

  • A test tube

  • A test tube holder

  • A sample of urine

  • Measuring cylinder

  • Burner

Procedure

  1. Take a sample of urine with the help of a measuring cylinder (2 ml).

  2. Pour the sample into a test tube.

  3. Pour 2 ml of Fehling’s solution A into the test tube containing the urine sample.

  4. Pour 2 ml of Fehling’s solution B into the test tube containing the urine sample.

  5. Securely hold the test tube and heat it on the burner for two minutes.

  6. Keep stirring the tube.

Conclusion and Observation

The formation of a green precipitate indicates the presence of sugar in the sample of urine. Based on the concentration of glucose in the sample, the urine sugar test will yield different colours every time.

Now you know how to do a urine sugar test. For more on other chemical tests and related topics, register and sign up for Vedantu’s free live classes today. You can also download our Vedantu app for convenient access to related notes and interactive online sessions.

FAQ (Frequently Asked Questions)

1. Which Reagent is Used to Detect Sugar in Urine?

Ans. Benedict’s solution is the reagent which is used to detect sugar in urine.

What Can Be Used to Detect Abnormal Levels of Sugar in Urine? What is this Condition Called?

Ans. Benedict's solution can be used to detect abnormal levels of glucose in the urine, in turn also assessing its concentration in our blood. The condition is called glucosuria. 

3. What Does the Presence of Glucose in Urine Indicate?

Ans. High levels of glucose in the blood, called glucosuria, is an indicator of diabetes mellitus. If unchecked, it can be detrimental to an individual’s health.