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  • To test for the presence of monosaccharides and reducing disaccharide sugars in food, the food sample is dissolved in water, and a small amount of Benedict's reagent is added. During a water bath, which is usually 4-moiety, after isomerization.
  • Sucrose (table sugar) contains two sugars (fructose and glucose) joined by their glycosidic bond in such a way as to prevent the glucose isomerizing to aldehyde, or the fructose to alpha-hydroxy-ketone form. Sucrose is thus a non-reducing sugar which does not react with Benedict's reagent. Sucrose indirectly produces a positive result with Benedict's reagent if heated with dilute hydrochloric acid prior to the test, although after this treatment it is no longer sucrose. The acidic conditions and heat break the glycosidic bond in sucrose through hydrolysis. The products of sucrose decomposition are glucose and fructose, both of which can be detected by Benedict's reagent, as described above.
  • Starches do not react or react very poorly with Benedict's reagent, due to the relatively small number of reducing sugar moieties, which occur only at the ends of carbohydratechains. Inositol (myo-inositol) is another carbohydrate which produces a negative test.
  • Benedict's reagent can be used to test for the presence of glucose in urine. Glucose found to be present in urine is an indication of diabetes mellitus. Once a reducing sugar is detected in urine, further tests have to be undergone in order to ascertain which sugar is present. Only glucose is indicative of diabetes.
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Q: Is Benedict test positive in diabetics?
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Does skim milk test positive with the benedict's test?


Why is the Benedict test not exclusive to glucose?

The Benedict test is not exclusive to glucose because it can detect the presence of reducing sugars in general. This means that it can also detect other reducing sugars such as fructose, lactose, and maltose, in addition to glucose. The test relies on the reduction of Cu(II) to Cu(I) in the presence of reducing sugars, forming a colored precipitate.

What is the indicator and color change for a positive test for glucose?

Benedict solution is the chemical indicator for simple sugars.

Why sucrose does not give a positive Benedict's test but hydrolyzed sucrose does give a positive beneditcts test?

Sucrose does not contain a free aldehyde or ketone group needed to reduce Benedict's reagent, so it does not give a positive Benedict's test. When sucrose is hydrolyzed into glucose and fructose by acid or enzymes, the resulting glucose can then react with Benedict's reagent due to the presence of the free aldehyde group, producing a positive test result.

Will fructose give a positive benedict's test?

Yes! Fructose is a reducing carbohydrate.

Is it possible for a solution to test positive in Benedict's test and negative in barfoed's test?

No! Its not possible for a solution to test positive for benedict`s and test negative for barfoed `s test as both detect the presence of reducing sugars and the only difference between the two tests is that further confirmation of a mono or disaccharide is done in barfoed ` s test.

Does starch gives positive result for Benedict test?

Starch is made up of repeating glucose units. Though it is a non reducing sugar, its hydrolysis gives out pure glucose, which is known as dextrose. And glucose, as we know, is a reducing sugar and hence would give a positive result in Benedict's test.

What is a positive test for carbohydrates?

These are the carbohydrate tests that would give a positive result on maltose: 1.Molisch test 2. Fehling's Test 3. Benedict's Test 4. Nylander's Test 5. Tollen's Test 6. Seliwanoff's Test 7. Barfoed's Test

Why did a solution of saliva and oats test positive with benedict's test and iodine test if the oats alone tested positive only in the iodine test and the saliva alone was negative for both?

polysaccharides and simple sugar

Why is the Benedict's test is positive when water starch and HCl keep for 30mins?

The Benedict's test is positive when it changes color from blue to orange or red in the presence of reducing sugars like glucose. In this scenario, the breakdown of starch into glucose by the hydrochloric acid (HCl) during the 30-minute incubation allows the glucose to react with the Benedict's reagent, resulting in the color change.

Will mannose produce a positive Benedict's test?

Mannose is a monosaccharide (an aldose) with the chemical formula C6H12O6.Being a a monosaccharide mannose react with the Benedict reagent.

Will Maltose produce a positive Benedict's test?

Yes, all monosaccharides do.