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The functioning of cells, tissues and body organs are regulated by endocrine system. The system ensures that there is a stable internal environment even when there are changes taking place within or outside the body. Endocrine cells produce hormones as a result of sensing the change in the internal environment. The hormones which are usually carried around the body are attached to specific and there is detachment upon arrival at the target cells.

In most cases hormones regulation in the body is usually by negative feedbacks, where by the production of a particular is stimulated when the hormone is needed and in case the supply of the particular hormones is enough, its production is inhibited

Some diseases are associated with over-secretion or under-secretion of hormones. Through measurement of level of a particular hormone in the bloodstream of a patient with a particular disease and comparing it with the hormone level in the blood of a healthy individual, the presence of the disease can be diagnosed. The regulation of some internal environment involve secretion of two hormones. In blood sugar regulation there is secretion of pancreatic insulin and glucagon which act in opposite direction in order to bring blood glucose to the required level.

The objectives of this experiment was to investigate the blood glucose level variation associated with different sources of glucose and to find the GI values for bread and yoghurt.


  1. Variation of BG with type of food

Null hypothesis: there is no difference in BG levels for pure glucose, bread and yoghurt.

Alternative hypothesis: there is a difference in BG levels for pure glucose, bread and yoghurt.

  1. Glucose variation in time intervals

Null hypothesis: There is no variation of BG level within the time intervals

Alternative hypothesis: There is a variation of BG level within the time intervals for each of the glucose sources.

The process of measuring the blood glucose involved the test strip being inserted into the BG monitor the capillary blood sample was collected by a finger stick. This involved the fingers being warmed first, then the skin of the thumb or fore finger was swabbed with alcohol and air dried. The hand was held downwards, and then the finger was pricked with a sterile lancet. After a drop of blood had welled up on the skin surface, it was transferred in one go through application of the finger to the underside or edge of a test strip. The result was recorded in a table under column time 0 on a designated computer in addition to recording of the monitor number.

The subject then consumed 50g glucose which was dissolved in 250ml of flavoured water after which they were to wash their hands to make sure that no glucose remained on their fingers. After consuming the drink blood was samples were collected at 30minutes interval for 2 hours and the BG concentration recorded in the table.

The second experiment was performed 1 week after the first experiment. It involved the subjects consuming 50g of carbohydrates in test foods of yoghurt and whole meal bread. Just like in the first experiment it was a requirement that the subjects to fast for six hours with only drinks without sugar being allowed to be taken. The monitor with the same number as in experiment 1 was used as a way of minimizing variability.

The test strip was inserted into the monitor and the procedure for collecting blood samples and testing was done as in experiment 1. The result was recorded in table2 under time 0 on a designated computer.

The subjects were then divided in two groups where group A members consumed 50g of CHO in the form of whole meal while Group B consumed 50g of CHO in the form of low fat yoghurt. It was a requirement that the food to be eaten in the shortest time possible. Blood samples were taken from the subjects in 30 minutes intervals for 2 hours. The BG was measured and recorded in table and on a designated computer. After obtaining BG values, the AUC for the reference food and test foods were determined using the excel macro and the values entered in a table on a designated computer.

The analysis of the BG levels are summarized in table 4 and figure 1. From the figure it can be seen that there was variation BG values for the different types of food when a particular time interval is considered. Looking at 30 minutes interval it can be observed that glucose had the highest value of 8.18, the BG value for bread was 7.4 while the value BG value for yoghurt was lowest at 6.79. It is also observed that there was variation of BG levels with time. Focusing on glucose BG values were 4.93, 8.18,8.56,7.28 and 6.52 for fasting, 30 minutes, 60 minutes , 90 minutes and 120 minutes respectively. There was also variation in BG levels for yoghurt and bread. From the table 6 and figure 3 it is clear that the BG level for glucose was highest in all the time intervals and also the BG levels was high in bread in all the time intervals when compared to BG levels in yoghurt.

The GI values for bread and yoghurt are given in table 5 and figure 2. From the figure it can be seen that the GI value for bread was very high with a value of 75.88 as compared to the yoghurt GI value of 46.62. From the table 5 it can be seen that there was a big variation in the GI values for the individuals’ GI values as shown with the large standard deviation values in both yoghurt and bread GI values.


From the experiment glucose registered the highest BG level as compared to the other foods. This was expected because glucose is directly absorbed into the blood streams thus resulting in the high concentration. On the other hand the glucose in the other food is not readily available for absorption and this leads to the lower BG values. This is because the food has to be digested by enzymes in order to be converted to glucose before being released into the blood stream. It was also observed that the BG values varied with time with the highest values being registered at 60 minutes in glucose while for yoghurt and bread the value was maximum in 30 minutes and there after the was reduction in the BG levels to the lowest levels at 120 minutes. The trend can be explained by the fact that after glucose being absorbed into the blood stream the level was above the optimum level and there was need to reduce it. This was done by leasing insulin into the system which ensured that the BG level was reduced.

There was high variability in individuals BG values and various reason can be given for this. The process of digestion in each individual may vary with some people having a digestive system that will digest the food fast and releasing the food into the blood stream faster compared to other individual. The ease with which the food is digested could also depend on the state it was released from the mouth. Proper chewing of the food ensures the food is reduced into very small pieces and this ensures faster digestion. This variations could explain the high variability in the individuals BG levels and also the variability in BG in the three sources of glucose consumed. The variability of BG values in some of the individuals could be due to their health status with those who are diabetic having the highest values of BG being registered. This is due to the fact that the individuals’ body system does no have the ability to regulate BG levels. The high GI value in bread compared to that of yoghurt can be explained in the difference of CHOs in the two types of food with those in bread having high digestion rates to glucose as compared to the lower digestion rates of CHOs in yoghurt.

Table 4: Mean BG values and standard errors for glucose, bread and yoghurt at various time intervals

Time interval

Food type

Std. Error


Figure 1: Bar graph for mean BG values for glucose, bread and yoghurt at various time intervals

Table 5: Dependent Variable: GI Value

Type of food

Std. Deviation





Figure2: Mean GI value for yoghurt and bread

Tables 6: Mean BG values in glucose, bread and yoghurt at various time intervals


Figure 3: Comparison of BG values in glucose, bread and yoghurt


Susman J (1997). Reducing the complications of type II diabetes: a patient-centered approach. Am Fam Physician

Mayfield, M.D (2002).Diagnosis and Classification of Diabetes Mellitus: New Criteria Bowen Research Center, Indiana University, Indianapolis, Indiana