Characteristics of Glucose - Preprandial - Postprandial

By Prev Info - February 11, 2022

Characteristics of Glucose

Glucose appears in plants and animals through two different methods of production.

Glucose is a form of energy used in plants and animals. The process by which energy is used is oxidation. Physical and chemical characteristics allow glucose to work in the oxidation process the way it does in animals. Photosynthesis is the process used by plants to turn glucose to energy.

Physical Characteristics

The physical characteristic of all forms of glucose is that it is colorless. Glucose's molecular weight is 180.18.

Chemical Characteristics

The chemical name for glucose is 6-(hydroxymethyl)oxane-2,3,4,5-tetrol. The chemical makeup of glucose is six carbon atoms, 12 hydrogen atoms and six oxygen atoms to makeup one molecule of sugar and is written as C6H12O6. Glucose is a simple monosaccharide sugar. High-energy bonds hold the glucose molecule together until the bond is broken and releases energy.


In order for a body to use energy, the process of glucose oxidation must take place. Oxidation is the process by which energy is obtained from glucose. It is written as C6H12O6 + 6O2 --> 6O2 + 6H2O. In order for a body to use energy, the process of glucose oxidation must take place. Oxidation is the process by which energy is obtained from glucose. It is written as C6H12O6 + 6O2 --> 6O2 + 6H2O. Glucose oxidation, also known as glycolysis, is the first step. At this time, six-carbon glucose molecules are split into two three-carbon pyruvate molecules. From here, other processes take the glucose to different forms to be stored as ATP for later use.


Glucose can also be produced in plants through a process called photosynthesis, which occurs in chloroplasts in the plant leaves. Plants use sunlight as the energy sources needed to turn carbon dioxide and water into glucose. Glucose serves many functions in a plant. Because plants cannot store a lot of glucose, they turn it into starch to be converted back to glucose and used later. Glucose can also turn into fat and proteins used by a plant.

ATP & Glucose 

Your body needs both glucose and ATP (short for adenosine triphosphate) for energy. Glucose is a type of sugar found in carbohydrates. Your body breaks down glucose to produce ATP.


Plants take in the solar energy of the sun and convert it to chemical energy through a process called photosynthesis. You then take in this chemical energy whenever you consume vegetables (or carbohydrates).


The first phase in the process of releasing the energy stored in carbohydrates is digestion. Digestion works to break down carbohydrate molecules into sugar (usually glucose). Once digestion is complete, glucose gets absorbed into your bloodstream, transported throughout your body and taken up by your body's cells. Here the process of cellular respiration takes over to produce ATP.


Cellular respiration works to break down the chemical bonds of the glucose molecule, releasing the stored chemical energy. The energy released from glucose is used to power the manufacturing of ATP.


Your body doesn't actually run on glucose. Glucose is just a fuel. ATP is the true energy currency of your body.

Other Types

The other two types of energy-containing food molecules, fats and proteins, are synthesized by both plants and animals using carbohydrates as a base. Through cellular respiration your body also breaks down fats, and sometimes protein, to use the energy contained in the chemical bonds of these molecules to manufacture ATP. But the glucose coming from carbohydrates is your body's primary fuel type.


Fruits That Contain Glucose

Glucose is present in a wide variety of fruits.

Glucose is vital for the human body as it is your main energy source and is the only fuel normally used by the brain. It is a simple sugar, or monosaccharide, which means it is one of the most basic types of carbohydrate. Glucose travels through the human body in the blood stream and is often referred to as blood sugar. You ingest glucose when you eat. Some foods already contain glucose, while other foods will contain more complex carbohydrates, such as starch, that need to be broken down into glucose by the digestive system before it can be used.

Many fruits contain a variety of different sugars, both complex and simple, including glucose, fructose and starch. However, although the consumption of sugar is often linked to weight gain, for most people the health benefits of fruit far outweigh its carbohydrate content. 


Dates contain significantly more glucose than most other fruits. Dates are 32 percent glucose. While starch is not found in dates, 23.7 percent of it was made of fructose and 8.2 per cent of sucrose, both of which are other forms of sugar. Dates also have a relatively high glycemic index, or GI. This is a measure of how quickly glucose is released into the blood stream by certain foods. Dates have a GI of 103, and foods with a low GI are the best for controlling blood sugar swings and encouraging brain function and concentration, so dates may not be the best fruit to eat for sustained energy.

Cantaloupe Melons

Cantaloupe melons whave a small amount of glucose compared to dates. They consist of a relatively small amount of fructose at 0.83 per cent, while 3.26 per cent of the fruit is sucrose.


Apples contain significantly less carbohydrates than dates. Glucose made up for around 2 percent of the composition of each variety of apple. Apples are also one of the only fruits that contain starch. Apples contain a larger proportion of fructose to glucose, with the sugar accounting for 7.25 percent of Empire eating apples. The most "intestinal friendly" foods tend to be those that contain a larger amount of glucose to fructose. This means that apples may be less suitable for those with irritable bowel syndrome.

However, they may be a good choice of fruit for those with diabetes or people who are looking for food to help them concentrate, as the Franklin Institute reports they have a lower GI of 38.


Bananas are 5.82 percent glucose, 3.78 percent fructose and 6.58 percent sucrose. They also contain starch, which made up 3.82 per cent of the fruit. Bananas also contain fiber and provide an instant boost of energy. This fruit has a relatively high GI of 62.

Define Preprandial Glucose

In diabetes blood glucose monitoring, preprandial means "before a meal." It is also known as the fasting glucose level. The more time that has elapsed since your last meal, the less effect that meal has on your preprandial glucose reading.


The lowest preprandial glucose reading usually occurs just before the first meal of the day. Sleep extends the period of time since your previous meal.


Preprandial glucose readings below 100 mg/dl indicate somebody who does not have diabetes. Fasting glucose readings between 100 mg/dl and 125 mg/dl indicate somebody who is pre-diabetic. Anyone with blood glucose readings over 125 mg/dl is considered a diabetic.

Time Frame

In a non-diabetic, it takes about two hours to return blood glucose levels to below 140 mg/dl after a meal. For diabetics, the time it takes to return to preprandial glucose levels varies depending on the severity of the diabetes.


The longer it takes for blood sugar levels to return to preprandial levels after a meal, the more damage is being done by high blood sugars.


Eating less sugar lowers the preprandial glucose over time and reduces the chances of long-term complications from diabetes.

Definition of Postprandial Glucose

Postprandial means "after the meal." Patients measure postprandial glucose levels within two hours after eating. Glucose levels in the blood are at their highest after a meal due to consumption of dietary sugar from food.


As the amount of sugar in the blood increases during a meal, the pancreas secretes insulin to tell the body to consume the glucose in the bloodstream.


If high amounts of sugar remain in the bloodstream after a meal, some of the body's processes become interrupted. For example, excess glucose molecules attach themselves to proteins in the blood, which disrupt their function.


In diabetics, the cells do not respond as well to the insulin produced by the pancreas, which is called insulin resistance. Also, the pancreas in diabetics is sometimes too impaired to produce enough insulin.


The glucose tolerance test uses postprandial glucose levels to diagnose diabetes. Doctors diagnose diabetes in a patient when his blood glucose level stays above 200 mg/dl two hours after consuming a sugary drink.


Exercise, lower consumption of dietary sugar, and weight loss contribute to lower postprandial glucose levels.

Difference Between Glucose & Triglycerides

Both glucose and triglycerides are metabolized by the body and carried throughout the bloodstream. They both can be made into energy sources for the body. They both can also lead to life-threatening conditions if produced in excess. However, both glucose and triglycerides have different breakdowns and uses in our bodies.


Glucose is a metabolized form of sugar in the body. It can be found in fruits or hydrolyzed from starch. When we digest food, we break down the starch and sugar from these foods into glucose. Glucose becomes an energy source that enters into the bloodstream.

Unstable Glucose

If the body produces too much or too little glucose, many systems and functions in the body may be affected. Diabetes is a widespread condition related to imbalanced glucose levels.


Triglycerides are the product of animal and vegetable fats stored by the body. The substance is made of three fatty acids combine with glycerol.Triglycerides are not only produced by eating fats, but also by eating carbohydrates. In the human body, these are carried through the blood stream and are used as an energy source.

Unstable Triglycerides

High triglycerides in the blood stream is defined as hypertriglyceridemia. It's linked to an increase of cardiovascular disease, obesity and pancreatitis. It is possible that diabetes is another consequence of high triglycerides.

Taking Control of Both

Your doctor can perform simple blood tests to determine your glucose and triglyceride levels. If your levels are higher than recommended, both can be lowered by a sensible diet and daily exercise; in some cases medication may be required.

A1c Vs. Glucose

Both A1c and blood glucose help you manage your diabetes.

If you have diabetes and measure your blood glucose at home with a hand-held glucometer, the result shows the amount of glucose in your blood at a given moment. The A1c is a laboratory test that measures the average amount of the extra glucose in your blood during the past two to three months.


Your glucometer gives a reading in milligrams of glucose in a deciliter of blood, written as mg/dl. A1c lab results are expressed as the percentage of hemoglobin molecules with glucose bound to them.


In order to effectively manage your diabetes, you need to know how you're doing on a particular day (mg/dl) and how you're doing overall (A1c).


Patients had trouble understanding that an A1c of 8.1 percent translated to a blood glucose of 186 mg/dl, so researchers developed the eAG.


Like the A1c, the eAG reflects average glucose levels over the past two to three months, but is reported in the same mg/dl as the readings from your glucometer. This is the measurement recommended by the American Diabetes Association (ADA).


There's an easy-to-use online calculator on the ADA site to translate your A1C reading into an eAG level.



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