The goal of the investigation was to explore the effect of caffeine on the blood glucose level. It was hypothesised that taking coffee reduced the blood glucose level and hence improved hyperglycemia. There were two hypotheses in the investigation. The first hypothesis was “the ingestion of coffee reduced the development of hyperglycemia in KK-Ay mice,” whereas the second hypothesis was “caffeine ameliorated insulin resistance in type 2 diabetes mellitus in KK-Ay mice” (Yamauchi et al., 2010).
The control groups were made up of eleven 4-week old KK-Ay mice in the first experiment and 5 mice in the second experiment, which were given plain water during the entire experimental period. These were the controls because they were not treated with the factor under investigation, but were needed to prove that the experiment was successful.
The treatment groups consisted of ten 4-week old KK-Ay mice in the initial experiment and five mice in the second experiment, which were given coffee mixed with water in the ratio of 1:1. These were the treatment groups because they were given the component whose hypoglycemic effects were being investigated (coffee).
In scientific experiments, the control groups were necessary to ensure that the observed effects were due to the administered treatments and not other extraneous factors. In the experiment, the two sets of mice ate similar foods and were maintained under identical conditions. The only difference between the two groups was the administration of plain water to one group and the administration of a mixture of water and coffee to the other group.
It was evident that the scientists used the scientific method in their experimental design. They began with the statement of the problem where they identified type 2 diabetes as the key cause of “high rates of morbidity and premature deaths” (Yamauchi et al., 2010, p. 5597). They further observed that an elevated coffee intake was associated with a decline in incidences of type 2 diabetes.
Therefore, they sought to validate the ability of coffee to ameliorate hyperglycemia and the possibility of exploiting of caffeine as a therapeutic agent in type 2 diabetes. They then proposed hypotheses of the study and ensured that they included controls in their experiments. They further ensured the reproducibility of the results by including replications of each experimental unit (mice).
This was evident in their choice of 11 control and 10 experimental mice in the first experiment as well as the use of 5 control and 5 experimental mice in the second experiment (Yamauchi et al., 2010). The results were clearly presented and highlighted the differences in addition to the similarities between the control and experimental groups. The analysis of the data used statistical methods. The information was expressed as means and standard error of means, which gave strength to the validity of the observations.
There was no bias in the experiments because all the factors were kept constant throughout the study in the experimental and control units. The type of food, feeding habits, age, and temperature were kept constant for the controls and the experimental mice. In addition, similar clinical tests were carried out on both groups. The only different treatment was the addition of caffeine to water given to the treatment groups. This was the key factor under investigation.
The hypotheses were supported by the observations of the study. It was realized that the blood sugar concentration was significantly lower in the group of mice that received coffee than in the control mice. It meant that the intake of coffee reduced tolerance to insulin thereby increasing its effectiveness (Coffee and type 2 diabetes, 2006).
Consequently, glucose in the blood was utilized by the tissues of the mice thus reducing its concentration in the blood. These observations were in line with the proposed hypotheses. It was concluded that caffeine ameliorated hyperglycemia by reducing insulin tolerance.
References
Coffee and type 2 diabetes. (2006). Web.
Yamauchi, R., Kobayashi, M., Matsuda, Y., Ojika, M., Shigeoka, S., Yamamoto, Y., Tou, Y., Takashi, I., Katagiri, T., Murai, A., & Horio, F. (2010). Coffee and caffeine ameliorate hyperglycemia, fatty liver, and inflammatory adipocytokine expression in spontaneously diabetic KK-Ay mice. Journal of Agricultural and Food Chemistry, 58(9), 5597-5603.