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The Effect Of Carbohydrates On Blood Glucose Levels Biology Essay

The World Health Organization defines diabetes as a chronic disease that occurs when the pancreas does not produce enough insulin, or when the body cannot effectively use the insulin it produces.

Diabetes mellitus, more commonly referred to as diabetes affects around 250 million people worldwide, although this number is expected to be considerably higher because “at least 50 percent of all people with diabetes are unaware of their condition” (Loughrey, 2008).

Previously, it was believed that “more women have been affected by diabetes than men” however, recent information has shown that these statistics are constantly changing (Springhouse, 2006).

As research has advanced and more information has become available on this subject, scientists have been able to identify several types of diabetes: Type 1, Type 2 and Gestational Diabetes.

Formerly called Insulin-Dependent Diabetes Mellitus (IDDM), Type 1 diabetes is “much less common and usually associated with children and teenagers” (Elliot-Wright, 2005) with statistics suggesting that it “accounts for between 5 to 15 percent of all people with diabetes” (Loughrey, 2008).

Type 1 diabetes is also more likely to develop in “Caucasians in northern climates… that have a genetic disposition toward the disease” (Rubin, 2008), when exposed to other environmental triggers, for example lack of exercise or a poor diet.

Considered an ‘autoimmunity’ disease, people diagnosed with Type 1 struggle to control glucose levels because their “immune system destroys the beta cells” (Bradley et al, 2006), after mistaking “…the insulin-producing cells of the pancreas as foreign bodies” (Hanas, 2004).

The production of insulin within the body is essential for “…maintaining stability in the body by preventing breakdown of proteins (found in muscle) and fats” (Bilous, 1999).

This is why it is vital for sufferers of Type 1 diabetes to take injections for the remainder of their lives, to help keep sugar levels within a normal range (Moran et al., 2004).

In contrast, Non Insulin-Dependent Diabetes Mellitus (NIDDM) now recognised as Type 2 which affects around 90% of all sufferers of diabetes, was believed to occur in adulthood (Van de Graaff et al, 1995), although there is an ever growing number of children being diagnosed with Type 2 diabetes in this day and age.

Obesity is believed to be the major cause of Type 2 diagnosis although research has indicated that “about 10 percent of people with Type 2 diabetes are not overweight” (Brill, 2008).

Type 2 diabetes can occur when the body produces too little insulin, making it difficult to convert the glucose into sufficient energy or if someone is suffering from insulin resistance, which is when the body is unable to use the insulin stored effectively. Insulin resistance normally occurs many years before further symptoms of diabetes are identified. At the onset of Type 2 diabetes, “treatment is with diet with or without tablets”; but a few years after the initial diagnosis, insulin is “…nearly always used because of the progressive nature of this condition” (Fox et al., 2007).

The final type of diabetes is known as gestational diabetes, which occurs when a pregnant woman cannot “meet the demands of her growing body and growing baby.” This is because during the last three months of pregnancy, the body needs to produce “between three and four times as much insulin as it did before” (McCulloch, 2008). Difficulties producing the required level of insulin can lead a rise in blood glucose levels, thus causing diabetes. Gestational diabetes is much harder to detect since many of the symptoms such as feeling lethargic, thirsty and frequent urination are normal signs for most pregnant women.

Although difficult to identify, some studies have shown that various factors can increase the risk of a women suffering from gestational diabetes, for instance, “…obesity; a family history of diabetes; having given birth previously to a very large infant; a stillbirth… or having too much amniotic fluid” (National Institutes of Health, 1994).

Unlike both Type 1 and Type 2 diabetes, gestational diabetes “affects less than 1 in 20 pregnant women…” and “usually seems to disappear once the baby is born” (The National Health Service, 2009).

Investigations have also shown that people that suffer from gestational diabetes are at increased risk of developing Type 2 diabetes later on in life, when the production of insulin in the body deteriorates.

Hypotheses:

The two hypotheses under investigation are: “40 minutes after ingestion, blood glucose levels from starch are the same as for glucose” and “After 160 minutes, glucose levels are at baseline values.”

Aims:

The main purpose of this assignment was to produce graphs from the previously collected results, before analysing the data and either proving or disproving the two hypotheses stated.

Methods:

As outlined in the lecture notes (Ahmed, 2010).

Results:

Glucose Concentration (mM)

Absorbance (515nm)

0

0

1

0.09

2

0.19

3

0.32

4

0.42

5

0.43

6

0.55

7

0.68

8

0.77

9

0.82

10

0.98

Figure 1.1: Table 1 – Standard curve for Trinder’s Glucose Assay

Carbohydrate

Absorbance (515nm)

Glucose

White Bread

Subjects

Time (Minutes)

Time (Minutes)

0

40

80

120

160

0

40

80

120

A

0.60

0.88

0.74

0.70

0.44

0.52

0.65

0.67

0.55

B

0.48

0.79

0.51

0.44

0.46

0.50

0.55

0.66

0.56

C

0.56

1.00

0.52

0.78

0.41

0.51

0.67

0.65

0.74

D

0.48

0.57

0.48

0.42

0.46

0.60

0.61

0.60

0.55

E

0.43

0.64

0.47

0.40

0.43

0.52

0.43

0.65

0.53

F

0.38

0.76

0.67

0.61

0.59

0.47

0.63

0.73

0.58

G

0.35

0.97

0.95

0.50

0.41

0.55

0.77

0.66

0.49

H

0.56

0.80

0.65

0.60

0.53

0.48

0.56

0.58

0.60

Figure 1.2: Table 2 – Effect of carbohydrate on blood glucose levels.

Figure 1.3: This graph shows a standard curve for the results of Trinder’s Glucose Assay, measuring how absorbance changed as the concentration of glucose increased.

Figure 1.4: This graph shows the change in absorbance of two carbohydrates (glucose and white bread) over time for Subject A.

Figure 1.5: This graph shows the change in absorbance of two carbohydrates (glucose and white bread) over time for Subject B.

Figure 1.6: This graph shows the change in absorbance of two carbohydrates (glucose and white bread) over time for Subject C.

Figure 1.7: This graph shows the change in absorbance of two carbohydrates (glucose and white bread) over time for Subject D.

Figure 1.8: This graph shows the change in absorbance of two carbohydrates (glucose and white bread) over time for Subject E.

Figure 1.9: This graph shows the change in absorbance of two carbohydrates (glucose and white bread) over time for Subject F.

Figure 1.10: This graph shows the change in absorbance of two carbohydrates (glucose and white bread) over time for Subject G.

Figure 1.11: This graph shows the change in absorbance of two carbohydrates (glucose and white bread) over time for Subject H.

Discussion:

The first graph used Trinder’s Glucose Assay to assess how the absorbance changed as the concentration of glucose steadily increased. After drawing a line of best fit onto the standard curve, the results showed a strongly positive correlation between the two variables measured.

Occasionally, the results did not increase significantly between the two points, for example between the glucose concentrations of 4mM and 5mM, the absorbance only increased by 0.01, whereas, the average increase between the other sets of points was approximately 0.1.

The graph for Subject A (see Figure 1.4) showed that the absorbance for glucose is much higher throughout the experiment, when compared against the absorbance of white bread. The absorbance of glucose for this particular subject peaks at 40 minutes, with a value of 0.88, before quickly decreasing and ending with a value significantly lower than the baseline value. On the other hand, the values for the absorbance of the white bread were lower than the respective results for glucose right up until the end, when it rose to 0.72. This suggests that although it took much longer for the glucose to be absorbed into the body, the white bread still provided a good source of energy.

The graph for Subject B (see Figure 1.5) produced similar results with the main difference being that the peak in the results for the absorbance of white bread was at 80 minutes. Unlike Subject A, the absorbance for glucose decreased to its lowest value at 120 minutes (0.44) after reaching a peak at 40 minutes, yet it started to rise again at around 160 minutes, which would imply that the body had probably stored the excess glucose earlier, and now needed to use it as levels were too low.

The graph for Subject C (see Figure 1.6) produced erratic results for the glucose absorbance, as the values fluctuated every 40 minutes when it was measured. This could signify problems with retaining glucose in the body such as Impaired Glucose Tolerance (IGT), which is believed to be linked to a higher chance of contracting Type 2 diabetes. The absorbance of the white bread followed the expected pattern and rose slower than the absorbance of glucose, but unlike the previous two graphs, the value fell steeply at 160 minutes, just like the absorbance value for glucose.

The graph for Subject D (see Figure 1.7) produced results that were incongruous to the results collected for the other subjects. This is because the absorbance level for white bread remained higher than the absorbance level for glucose for the entire period of 160 minutes; however, the structure of the lines for both glucose and white bread were similar in shape. These results suggest that the patient could be suffering from hyperglycaemia, due to a higher amount of insulin in the body therefore causing the process of breaking down polysaccharides to speed up.

The graph for Subject E (see Figure 1.8) showed that after the ingestion of 50 grams of white bread, the absorbance level dropped. After the next measurement at 80 minutes, the absorbance levels for white bread showed similarities to that of the glucose, although slightly delayed.

The graph for Subject F (see Figure 1.9) displayed characteristics that resemble the majority of results for the other subjects, although the one main difference is that the absorbance level for glucose did not return to the baseline value (0.38) after 160 minutes. In contrast, the absorbance of white bread increased after ingestion, reached its peak at 80 minutes and then fell to 0.47 after 160 minutes, the same value that it started off as after fasting overnight.

The graph for Subject G (see Figure 1.10) showed that the absorbance values for both carbohydrates reached their peak at 40 minutes, and then both steadily decreased. As the rate of absorbance for glucose started to level off between 120 and 160 minutes, the value for white bread started to increase again, although the final value was still significantly lower than the initial value.

The graph for Subject H (see Figure 1.11) was different to the others since the absorbance level for white bread continually escalated from 0.48 at the start of the experiment to 0.59 after 160 minutes. Additionally, the absorbance value for glucose was high, but returned to around the baseline value towards the end of the experiment.

Overall, the graphs tend to show that out of the two carbohydrates, the glucose is absorbed into the bloodstream much quicker than the white bread, although there are some exceptions (Subject D). Similarly, the absorbance levels for the white bread also increased between zero and 40 minutes, albeit much slower. Unlike the results from the glucose measurements, Subject E was an exception to this rule, as the absorbance value for the white bread decreased between the period of the start of the experiment and after 40 minutes.

The reason behind the process of white bread being absorbed into the bloodstream taking longer than glucose is because glucose is a monosaccharide, whereas white bread is a polysaccharide, which is defined by the Collins English Dictionary (1999) as “a carbohydrate which consists of a number of linked sugar molecules, such as starch or cellulose.”

Monosaccharides like glucose are more easily absorbed into the bloodstream as a source of energy as these are the simplest type of sugars, whereas, in order for polysaccharides such as white bread to be absorbed into the body for energy, it needs to be broken down by the process of digestion into several simple sugars first.

Conclusion:

Overall, the experiment shows a clear indication that carbohydrates are a good source of energy for the body, and are useful to help quickly raise the blood sugar levels for diabetics.

Factors such as diet and exercise mentioned earlier need to be taken into consideration, as these increase the risk of contracting “diabetes mellitus” in both children and adults alike.

The results disprove the first hypothesis, as the blood glucose levels for white bread tended to be lower than those for glucose. However, the second hypothesis was proven to be true for the majority of the subjects. Future research would be necessary in this field to prove conclusively that these are hypotheses and findings are wholly accurate.

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