If one ingests fiber before a meal and exercises after a meal, then the intensity of the postprandial blood glucose spike should be lessened.

Diabetes:

Diabetes is a disease in which blood glucose levels in the human body are not able to be controlled normally. When a meal is ingested, the human body will break down the proteins, fats, and carbohydrates in the food and reabsorb the important metabolites needed for organ function. The most important source of energy for organs is glucose. Glucose comes from the food that we eat. When food is digested into glucose, the glucose needs to enter the cells of the organs. This occurs with the help of a hormone called insulin. When blood glucose levels increase after a meal, insulin is signaled from the pancreas to be released and helps glucose in the bloodstream to enter the cells of our organs.  However, when insulin is deficient or defective, this cannot happen. As a result, glucose in the bloodstream builds up to unhealthy levels. There are two scenarios in which this can happen.  In the first scenario, the human body recognizes the insulin molecule as being foreign and launches an immune response against it.  As a result, insulin is depleted and there are insufficient levels. This is called Type 1 Diabetes. In the second situation, there is a defect that develops within the receptor of the insulin molecule, so the insulin cannot help glucose enter cells, causing blood sugar levels to increase. This is called Type 2 Diabetes^6,7.

An uncontrolled increase in blood glucose levels can result in a plethora of detrimental effects. Some of the most common complications are cardiac disease, vision loss (retinopathy), kidney failure, and peripheral neuropathy. Recent studies are also showing that increased blood glucose levels may also be leading to cancer. These diabetic complications eventually result in death^6,8.

Type I diabetics treat their disease through daily injections of insulin, which help in controlling blood glucose levels. However, there are numerous other ways that Type I and Type II diabetes can be further controlled. There are numerous risk factors that can cause the onset of diabetes. They are as follows:

• Age >40 years
• Elevated BMI (Body Mass Index)
• Elevated Cholesterol
• Elevated Blood Pressure
• Level of Physical Activity
• Ethnic Background (African, Arab, Asian, Hispanic, Indigenous, or South Asian)
• Family History of Diabetes
• Smoking & Alcohol

Managing the above risk factors properly can slow the progression of diabetes.

How Fiber Affects Blood Glucose Levels:

Fiber is a carbohydrate that has many health benefits, but there is evidence that soluble fiber, in particular, can help control blood sugar levels. Sources containing soluble fiber are fruits, vegetables, legumes, and wheat bran. Soluble fiber in water and forms a gel-like substance in the stomach. The viscosity of the contents in the stomach is increased and food stays in the stomach for longer. Movement of the bolus into the small intestine is also slowed. As a result, carbohydrates are also metabolized at a slower rate because the slowed movement and the fact that enzymes find it more difficult to mix into the gut contents with an increased viscosity. Glucose then enters the bloodstream more slowly. Normally, carbohydrates do not travel far down the small intestine since they are broken down rather quickly. However, when they are broken down more slowly due to the viscosity increase by fiber, they can make it to the distal ileum.  As a result, this triggers the ileal brake, which is the release of two hormones: GLP-1 and Peptide YY. These hormones actually cause the stomach to empty more slowly and cause food to move through intestines less rapidly. This feedback assists in slowing down digestion and also how quickly blood glucose increases after a meal. Furthermore, GLP-1 also increases insulin sensitivity which encourages cells in the body to take up glucose more efficiently².

How Exercise Affects Blood Glucose Levels:

There is also evidence that shows that exercise also helps in managing diabetes by controlling blood sugar levels. In general, glucose enters a cell by GLUT4. GLUT4 is a protein that allows for glucose to travel across a cell membrane. However, GLUT4 must get to the cell membrane first. The pathways that this occurs by are not fully understood.  However, there are 2 ways that GLUT4 can be upregulated to the cell membrane. The first way is by insulin itself.  Insulin in the blood will activate insulin receptors on cell membranes by binding to it. This activates the signalling cascade to upregulate GLUT4 to the cell membrane, which then allows for glucose in the blood to be taken up by a cell. The second method this pathway is initiated is by exercise. It is believed that the contraction of muscle cells also activates the upregulation of GLUT4 into the cell membrane allowing blood glucose to enter skeletal cells, thereby decreasing blood glucose levels^3,4,5.

In this study, I utilized low intensity exercise, such as walking, instead of high intensity exercise. High intensity exercise often causes the body to produce a stress hormone called cortisol. Cortisol is a hormone that releases stored glucose into the blood, which increases blood glucose. Therefore, high intensity exercise increases blood glucose levels.  As a result, this study used low intensity exercise instead¹³.

Revisiting the Scientific Question:

If fiber and exercise can decrease blood glucose levels after a meal, they would in turn, decrease the intensity of the postprandial glucose spike.  “Postprandial” is defined as after a meal. The “spike” is when the blood glucose level peaks. Therefore, the postprandial glucose spike in this study refers to the difference in the blood glucose levels when it peaks after a meal and the blood glucose level before the meal is started. With a less intense glucose spike and a lower number of glucose spikes on a daily basis, HbA1C levels can stabilize and even decrease. This is the concept of insulin resistance – with less glucose in the blood, insulin will not “wear out” and continue to work effectively. As HbA1C is controlled, it can be inferred that the overall risk and onset of diabetes could also then decrease in the long-term⁹.

The reason I chose fiber and exercise as the variables in this experiment is because they are easy to integrate into one’s daily life. This experiment was also done with a meal plan that the subjects already follow. This way, results of the experiment could be easily integrated into daily life and are more practical. Also,, it is very easy and practical to consume fiber before a meal and take a 20 minute walk after a meal.

Continuous Glucose Monitoring:

This study will utilize a continuous glucose monitor (CGM) to take blood glucose levels. The most ideal way to measure blood glucose levels is in fact to obtain a blood drop by finger prick and testing the glucose level by a glucometer.  However, since using human blood is not allowed in this study, I chose to use a continuous glucose monitor. A CGM consists of a small sensor that is a wire filament that is inserted into the skin using an applicator. This filament reaches the interstitial fluid under the skin.  The interstitial fluid is the fluid between the skin cells. The filament takes measurements based on the glucose concentration in this fluid, and does not reach the blood vessel that runs under the skin cells. The CGM above the skin is attached to a bluetooth transmitter, which then transmits the measurements to a receiver, which is typically a cell phone. The CGM can remain on the skin for upto 10 days. This study utilized the Dexcom G6 monitoring system which is a reliable system recommended regularly by doctors¹⁰.

 

The following are the variables in this study:

Manipulated Variables:

·   Fiber

·   Exercise

Responding Variable:

·   Blood Glucose Level (mmol/L)

Controlled Variables:

·   Type & Quantity of Meal

·   Type & Quantity of Fiber

·   Type & Length of Exercise

·   The Continuous Glucose Monitor

·   Blood Glucose Levels prior to the meal by restricting food/drink intake 2 hours before the meal.

·   The time the subjects wait to exercise after a meal

 

Materials:

• Continuous Blood Glucose Monitor – Dexcom G6
• Meal Plan:
  • Roti: 2
  • Broccoli & Potato Curry: ¾ cup for Adults; ½ cup for Children
  • Rice: ¾ cup for Adults: ½ cup for Children
  • Lentil Soup: ½ cup
  • 8 oz of Water
• Metamucil: 3 tsp in 240mL (Adults) and 1.5 tsp in 240mL (Children)
• Measuring Cups and Spoons
• Human Participants

Procedure:

       1)   Download Dexcom G6 Application onto cell phone.

       2)   Insert Continuous Blood Glucose Monitor as per instructions provided in the box.

GROUP 1: NO FIBER/NO EXERCISE – CONTROL

3)  Turn on the Dexcom application on a device. Ensure the application is synchronized to the CGM.

4)   Fast for 2 hours prior to meal.

5)   Record the blood glucose measurement (in mmol/L) before eating the meal. This is the preprandial measurement.

6)   Eat the meal as per the meal plan.

7)   Record the blood glucose measurement after the meal. It is important to wait for the glucose level to peak and come back down so the actual peak can        be established. This is the postprandial measurement.

8)   Repeat Steps 3-7 for two more days.

GROUP 2: FIBER/NO EXERCISE

9)   Turn on the Dexcom application on a device. Ensure the application is synchronized to the  CGM.

10)  Fast for 2 hours prior to the meal.

11)  Record the blood glucose measurement (in mmol/L) before eating the meal. This is the preprandial measurement.

12)  Ingest Fiber (Metamucil) as per directions on the packaging. Adults ingest 3 levelled teaspoons dissolved in 240mL of water. Children ingest 1.5                   levelled teaspoons dissolved in 240mL of water.

13)  Eat the meal as per the meal plan.

14)  Record the blood glucose measurement after the meal at its peak. This is the postprandial measurement.

15)  Repeat Steps 9-14 for two more days.

GROUP 3: NO FIBER/EXERCISE

16)  Turn on the Dexcom application on a device. Ensure the application is synchronized to the CGM.

17)  Fast for 2 hours prior to the meal.

18)  Record the blood glucose measurement (in mmol/L) before eating the meal. This is the preprandial measurement.

19)  Eat the meal as per the meal plan.

20)  After 10 minutes has passed upon finishing the meal, go for a walk outside for 20 minutes at a normal walking pace.

21)  Record the blood glucose measurement after the meal at its peak. This is the postprandial measurement.

22)  Repeat Steps 16-21 for two more days.

GROUP 4: BOTH FIBER/EXERCISE

        23)  Turn on the Dexcom application on a device. Ensure the application is synchronized to the CGM.

        24)  Fast for 2 hours prior to the meal.

25)  Record the blood glucose measurement in mmol/L before eating the meal. This is the preprandial measurement.

26)  Ingest Fiber as stated above in Step 10.

27)  Eat the meal as per the meal plan.

28)  After 10 minutes has passed upon finishing the meal, go for a walk outside for 20 minutes at    a normal walking pace.

29)  Record the blood glucose measurement after the meal at its peak. This is the postprandial  measurement.

        30)  Repeat Steps 23-29 for two more days.

This concludes the study for one subject. Repeat for all subjects.

 

The following are the results obtained from the experiment.

Note that results are in terms of percentages. This calculation was done by:

% Change in Blood Glucose = Postprandial Blood Glucose – Preprandrial Blood Glucose  × 100%                                                                                                                                                                             Preprandrial Blood Glucose

1. The control group on average had a 56% increase in blood glucose levels after eating a meal. The increase ranged among subjects from 42% - 78%.
2. The fiber only test group on average had a 30% increase in blood glucose levels after eating a meal. The range among subjects was between 26% - 40%. All subjects had a glucose spike with fiber that was lower than their respective control spikes.
3. The exercise only test group on average had a 28% increase in blood glucose levels after eating a meal. The range among subjects was between 17%- 41%. All subjects had a glucose spike with exercise that was lower than their respective control spikes.
4.  The fiber and exercise test group on average had a 24% increase in blood glucose levels after eating a meal. The range among subjects was between 11% - 43%. All subjects had a glucose spike with exercise that was lower than their respective control spikes.

 

The following is an analysis of the above results:

Result #1: Control Group – No Fiber/No Exercise

Explanation: Subjects in the control group had an average of a 56% increase in postprandial glucose levels. This is in the range of normal, as studies show that the postprandial glucose levels can increase anywhere from 41-94%¹⁴. Note that all subjects in this study are vegetarian and the diet utilized in this study was vegetarian only.

Inference: The postprandial glucose spikes fell within the normal range.

Result #2: Fiber Only Group

Explanation: Subjects in the fiber only test group on average had a 30% increase in the postprandial glucose spike. The range was from 26-40% for the subjects. The fiber only group spike was considerably lower than the control spike for every subject. On average, this group minimized the glucose spike by 26%.

Inference: Fiber minimized the postprandial glucose spike.

Result #3: Exercise Only Group

Explanation: All subjects in the exercise only test group had a postprandial glucose spike that was much lower than the subjects control spike. On average, the postprandial glucose spike increased by only 28% after a meal among subjects. This is a significant decrease when compared to the average increase in the blood glucose for the control group. On average, the group minimized the glucose spike by 27%. 

Inference: Exercise minimized the postprandial glucose spike.

Result #4: Fiber/Exercise Group

Explanation: All subjects in the fiber and exercise only test group had a postprandial glucose spike that was even lower than the spike in the fiber and exercise only groups. On average, the postprandial glucose spike increased by only 24% among subjects. Again, when compared to the control groups, this is a significant decrease in postprandial glucose.

Inference: Fiber and exercise together created the largest reduction in the postprandial glucose spike.

 

Various conclusions can be drawn from the results obtained from this study. In general, both fiber and exercise resulted in a reduction in postprandial glucose levels. However, the greatest reduction of the postprandial glucose spike, as compared to the control group, was in the fiber and exercise test group. This test group decreased blood glucose levels by 4% - 6% more than the fiber only and exercise only groups. Therefore, one can infer from this experiment that fiber and exercise alone and together assist in blood glucose control in a positive way.

 

The significance of this study is that it raises awareness to prevent the onset of diabetes. Here are real-life applications that can extend from this study:

·       Create a program for prediabetics to wear a CGM for a few months for them to be able to track how their diet and lifestyle affects their blood glucose. This will allow for prediabetics to deal with their condition in a more active manner and help them be more preventative.

·       An opportunity to improve CGM technology using artificial intelligence:

o   Create algorithms in which the technology can also track stress and sleep levels (ie. through oxygen saturations and heart rate). Stress and sleep patterns can then be linked with blood glucose levels to determine any significant correlations.

o   Can a CGM be created that can start detecting patterns in the blood glucose of the subject wearing the sensor using algorithms? The advantage of this is then allowing for the technology to detect relationships between diet and exercise and glucose levels. These patterns can then allow for the technology to provide insights and recommendations to the subject to help mitigate blood glucose levels and the onset of diabetes.

 

 

Sources of Error:

There could have been various sources of errors in this study. Some of these are as follows:

• The CGM by Dexcom is calibrated (as the manufacturer claims). The most accurate method to measure blood glucose is by using a glucometer which measures the blood glucose from a small drop of blood. However, since using blood was prohibited in this study, it could not be confirmed whether the CGM (which takes glucose measurements from the interstitial fluid) was truly accurate. Repeating this study using a glucometer and blood from a finger prick would be most accurate.
• Blood glucose levels could be affected by many external factors, such as stress or quality of sleep. Results obtained could have been erroneous since it is impossible to keep metabolic conditions in a human being the same every day of the experiment.

Further Experimentation:

Throughout my experiment, I came across several “further questions” that I would consider if I repeated my experiment. Here is some further experimentation that could be undertaken:

• Repeat the experiment with more test subjects.  100-200 test subjects would be ideal and increase accuracy of the results. A larger number of test subjects allows our statistical analysis to be more reliable. Particularly, test subjects with:
  • Varying health statuses
  • Varying lifestyles
  • Varying diets
• Repeat the experiment by using a glucometer and testing glucose from a drop of blood obtained by a finger prick.
• Repeat the experiment by employing higher intensity exercise to study the effects of cortisol on blood glucose levels.
• Repeat the experiment while tracking stress levels and sleep quality to make correlations between these two factors and blood glucose levels. Stress levels and sleep quality can be tracked by vitals such as oxygen saturation, heart rate, and blood pressure.

 

 

Sources Cited

1. IDF Diabetes Atlas, 2022, https://diabetesatlas.org/.
2. Newman, Tim. “Can Fiber Reduce Blood Sugar Spikes?” ZOE, 4 May 2023, https://zoe.com/learn/fiber-reduce-blood-sugar-spikes.
3. “How exercise can help lower your blood sugar.” Diabetes Canada, 2024, https://www.diabetes.ca/about-diabetes/stories/how-exercise-can-help-lower-your-blood-sugar.
4. Stanford, Kristin & Goodyear, Laurie. “Exercise and type 2 diabetes: molecular mechanisms regulating glucose uptake in skeletal muscle.” Advanced Physiology Education, 2014, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4315445/.
5. Syeda, Afsheen, Battillo, Daniel, Visaria, Aayush, & Malin, Steven. “The importance of exercise for glycemic control in type 2 diabetes.”American Journal of Medicine Open, 2023, https://www.sciencedirect.com/science/article/pii/S2667036423000018.
6. “What is diabetes?” CDC, Sept 2023, https://www.cdc.gov/diabetes/basics/diabetes.html.
7. “What Is Diabetes?” National Institute of Diabetes and Digestive and Kidney Diseases, April 2023, https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes.
8. “Disease Prevention.” Harvard T.H. Chan School of Public Health, 2024, https://www.hsph.harvard.edu/nutritionsource/disease-prevention/.
9. Freeman, Andrew, Acevedo, Luis, Pennings, Nicholas. “Insulin Resistance.” StatPearls, August 2023, https://www.ncbi.nlm.nih.gov/books/NBK507839/.
10. Umpierrez, Guillermo E. “Accuracy of Dexcom G6 Continuous Glucose Monitoring in Non–Critically Ill Hospitalized Patients With Diabetes.” Diabetes Care, 2021, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8323182/.
11. Asp, Karen. “Is High-Intensity Exercise Always Best for You? It Depends.” Real Simple, January 2023, https://www.realsimple.com/health/fitness-exercise/exercise-intensity
12. “High Intensity Exercise vs Low Intensity Exercise - Which Is Best?” Forth, 16 August 2021, https://www.forthwithlife.co.uk/blog/high-intensity-vs-low-intensity-exercise.
13. Thau, Lauren, Gandhi, Jayashree, Sharma, Sandeep. “Physiology, Cortisol.” August, 2023, https://www.ncbi.nlm.nih.gov/books/NBK538239/.
14. Sullivan, Debra. “What are ideal blood glucose levels?”. Medical News Today, 2023, https://www.medicalnewstoday.com/articles/317536.

I would first like to extend my appreciation to my school, Webber Academy, for giving me the opportunity to participate in the Science Fair. Furthermore, I would like to express my sincere gratitude to my Science teacher, Mr. Jason Baillie, for teaching me about the Scientific Method and guiding me with my project for the past few months. Finally, this work would not have been possible without the participation and diligent support of my family.