Difference Between Glucose and Fructose

Key difference - glucose vs. fructose

Carbohydrates are an essential macromolecule for all living things in the world and can be divided into three categories. They are monosaccharides, disaccharides, and polysaccharides. Glucose and fructose are considered to be the simplest and most common monosaccharides in the world. However, there seems to be a lot of confusion about the difference between glucose and fructose as they have a similar formula: C 6 H 12 O 6 . Both fructose and glucose are considered simple reducing sugars and are absorbed directly into the bloodstream during digestion. However, glucose is an aldo sugar, while fructose is a simple keto sugar . Fructose is used commercially in the food and beverage industry because of its low cost and high sweetness compared to glucose. This is the main difference between glucose and fructose. In this article, let's work out the difference between glucose and fructose in terms of their purpose, chemical and physical properties.

What is Glucose?

The word glucose comes from the Greek and literally means "sweet wine"; it is also known as grape sugar. Its molecular formula is C 6 H 12 O 6 . Compared to L-glucose, D-glucose is the predominant isomer in nature. It is the main product of the photosynthetic process, which uses water and carbon dioxide to produce glucose through plant chlorophyll pigments in the presence of sunlight. In addition, glucose is the most important energy-releasing compound in cell respiration and is more or less similar to the reversal of the photosynthetic reaction. Glucose is also used to synthesize some disaccharides and polysaccharides. It is used to synthesize starch in plants and glycogen in animals. In addition, it can be obtained by hydrolyzing carbohydrates including table sugar (sucrose), maltose, cellulose , glycogen, etc. Difference Between Glucose and Fructose

What is fructose?

Fructose is a simple keto sugar and is also known as fruit sugar because it is mainly found in many plants. Its molecular formula is C 6 H 12 O 6 . D-fructose is the predominant isomer in nature compared to L-fructose. It is the most reactive and water soluble sugar compared to other natural sugars. It can be isolated from honey , tree and grape fruits, flowers, berries and root vegetables. However, fructose is industrially produced from sugar cane, sugar beet and corn. Fructose is particularly important for the beverage industry and baked goods, as it helps improve palatability and taste, as well as browning or developing color.

Key difference - glucose vs. fructose

Difference Between Glucose and Fructose

The differences between glucose and fructose can be divided into the following categories. They are;


Glucose was first described by the German chemist Andreas Marggraf in 1747. However, it was largely investigated by Emil Fischer.

Fructose was first introduced in 1847 by the French chemist Augustin-Pierre Dubrunfaut.

Natural sources

Glucose is rarely stored in plants or animals because it is highly reactive. But glucose is the building block for starch (plant storage), glycogen (animal storage), cellulose (in the cell wall), sucrose (in nectar, vegetable treacle) and lactose (in milk).

Fructose is found in honey, tree and grape fruits, flowers, berries and most root vegetables.

Alternative names

Glucose is also known as blood sugar, dextrose, corn sugar, D-glucose, grape sugar.

Fructose is also known as fruit sugar, levulose, D-fructofuranose, D-fructose, D-arabino-hexulose.

IUPAC name

Glucose 's name is 2,3,4,5,6-pentahydroxyhexanal.

Fructose is called 1,3,4,5,6-pentahydroxy-2-hexanone.

Chemical structure

Glucose is both a hexose and an aldose and is therefore also known as aldohexose. Difference Between Glucose and Fructose - Structure 1

Fructose is a keto sugar with 6 carbon atoms and is also known as D-fructopyranose. Difference between glucose and fructose - structure 2

Commercial synthesis

Glucose is produced commercially by the enzymatic hydrolysis of starch.

Fructose is made commercially from sugar cane, sugar beet, and corn.

A product of photosynthesis

Glucose is the main product of photosynthesis.

Fructose is not a product of photosynthesis.

Water solubility

Compared to fructose, glucose is less water-soluble.  

Fructose is the water-soluble sugar of all types of sugar.

Control of appetite

Drinking lots of glucose results in higher circulating insulin and leptin levels and lower post-meal ghrelin levels compared to ingesting high-fructose beverages.

Drinking lots of fructose leads to lower circulating insulin and leptin levels and higher post-meal ghrelin levels compared to consuming high-glucose beverages, suggesting that consuming large amounts of fructose increases the likelihood of weight gain.

Glycemic Index

Compared to fructose, glucose has a high glycemic index.

Fructose has the lowest glycemic index (GI = 19) of all natural sugars including glucose.

Maillard reaction

Glucose goes through the Maillard reaction, non-enzymatic browning, with amino acids being slower than fructose.

Fructose has a Maillard reaction faster than glucose. Thus, it has the potential to play an important role in changes in food palatability, browning, and reduction in comparable tenderness during cake preparation and the formation of mutagenic compounds.


The sweetness of glucose is less than that of fructose

Fructose has a higher sweetness than glucose and shows a synergy effect in combination with other sweeteners.


Compared to fructose, glucose is somewhat easy to crystallize from an aqueous solution.

Compared to glucose, fructose is difficult to crystallize from an aqueous solution.

Hygroscopicity or water absorption capacity

Compared to fructose, glucose slowly absorbs moisture from the environment.

Compared to glucose, fructose quickly absorbs moisture from the environment.

Release of water

Compared to fructose, glucose releases moisture quickly into the environment.

Compared to glucose, fructose slowly releases moisture into the environment. Thus, fructose is considered a good humectant and retains moisture for a longer period of time and can contribute to a tastier texture and a longer shelf life for food products containing fructose.

Use as a sweetener

Glucose is used in making candies, breakfast bars, jujubes, marshmallows, and gelatin desserts.

Fructose is used in the manufacture of diet soft drinks, fruit beverages, diet soda, instant breakfasts, chewing gum, frozen desserts, gelatin desserts, juices, laxatives, chewable vitamin supplements, milk beverages, pharmaceuticals, and nutritional supplements.

To sum up, glucose and fructose are primarily simple sugars that are used as sweeteners. But fructose is an economically feasible and healthy food ingredient compared to glucose. However, the safety of long-term consumption of these natural sugars is still controversial.

Difference Between Glucose and Frutcose - Infographic


Boerio-Goates, Juliana (1991), Heat capacity measurements and thermodynamic functions of crystalline α-D-glucose at temperatures from 10 K to 340 K, J. Chem. Thermodynamik. 23 (5): 403-9.

Bray, GA (2013). Energy and fructose from beverages sweetened with sugar or high fructose corn syrup pose a health risk to some people. Advances in Diet: An International Review Journal 4 (2): 220–225.

Chapter 3: Calculating the Energy Content of Food - Energy Conversion Factors, Food Energy - Analysis Methods and Conversion Factors, FAO Food and Nutrition Paper 77, Rome: Food and Agriculture Organization, 2003, ISBN 92-5-105014-7.

Hyvonen, L. and Koivistoinen, P (1982). Fructose in food systems. In Birch, GG and Parker, KJ Nutritive Sweeteners. London and New Jersey: Applied Science Publishers. Pp. 133-144. ISBN 0-85334-997-5.

Malik, Vasanti S. and Hu, Frank B. (2015). Fructose and Cardiometabolic Health. American College of Cardiology Journal 66 (14): 1615-1624.

Image courtesy:

"Glucose metabolism" by Häggström, Mikael. "Medical Gallery by Mikael Häggström 2014". Wikiversity Journal of Medicine 1 (2). DOI: 10.15347 / wjm / 2014.008. ISSN 20018762. -Own work. (Public Domain) via Commons

"DL-Fructose num" from NEUROtiker - own work. (Public Domain) via Commons

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