Glucose- a monosaccharide- is one of the simplest sugars utilized as a primary source of energyat the cellular level. Glucose is essential because some vital organs such as the brain and the red blood cells wholly rely on it as an energy source.
With reference to glucose metabolism, the glycolytic pathway(figure 1) offers the fastest means to energy production. Hence in case of energy deficit the body will break down any available glucose prior to utilizing other sources of energy such as amino acids, pyruvate and glycerol. Glucose is usually preserved in the body as glycogen (polysaccharide) especially in the liver. During starvation or strenuous exercises, the glycogen stores are usually mobilized via a process called gluconeogenesis (a process that maintains blood sugar levels) to generate glucose when the blood glucose concentrations are low.
Blood sugar levels are usually regulated by two major hormones i.e. insulin together with glucagon. While glucagon increases blood sugar levels by converting stored glycogen to glucose when the glucose levels get too low; insulin decreases blood glucose levels by causing cells in the liver, fat tissue and muscles to take up and store glucose as glycogen in the liver and muscles. When the blood sugar levels are high, insulin inhibits glucagon (which would have stimulated production of the insulin) thus reducing blood sugar concentrations. The two hormones compliment each other thus work as a part of a feedback mechanism to maintain stable blood sugar levels.
However abnormalities in these regulatory hormones have severe repercussions. For instance, diabetes a disease associated with high blood sugar levels due to inadequate insulin production or inability of the cells to respond to insulin had affected 2.8% of the population worldwide as of the year 2000 . There are three types of diabetes; type 1 diabetes characterized by body failure to produce insulin; type 2 diabetes characterized by resistance to insulin and gestational diabetes in pregnant women. Abnormalities in glucose levels are known as hypoglycemia or hyperglycemia characterized by low levels of blood glucose and high blood glucose levels respectively. Several methods have been devised to monitor abnormalities in blood sugar levels, one of the most common methods is known as the oral glucose tolerance test which was used in this experiment and is described herein
Aim: To examine the effect of glucose consumption on blood glucose concentration.
Null hypothesis: There is no effect upon blood glucose concentration in the 2 hours after ingestion of 50g glucose.
Directional alternative hypothesis: Blood glucose concentrations increased in the 2 hours after ingestion of 50g glucose
The equipment used in this experiment were a blood glucose monitor, test strip and a sterile lancet.
Subjects had fasted for at least six hours before the modified oral glucose tolerance test and were only allowed to take drinks without sugar. A test strip was then inserted into the blood glucose monitor. To collect the sample, the subjects warmed their hands, swabbed the skin of their thumbs or forefinger tips with alcohol then allowed the swabbed part to air dry. After drying, they inclined their hands downwards and pricked the side of their sterilized fingers with a sterile lancet. Once a drop of blood appeared on the surface of the skin; they immediately transferred it onto the edge of the test strip and the result as indicated on the blood glucose monitor was recorded at time 0. The subjects then drunk 75g of glucose dissolved in 250ml flavored water then cleaned their hands to ensure no glucose remains on the hand. They recorded the time they finished the drink then pricked themselves againand transferredblood samples onto the test stripat 30 minutes intervals for 2 hours and recorded the blood glucose concentrations.
The results are provided in table 1 in the appendix. The experiment involved 99 subjects. According to the results, all subjects had their blood glucose levels within the expected baseline range i.e. ≤6.1mmol/l(mean:4.93232) except one whose baseline was 6.5mmol/l. 14 (14.14%) of the subjects had their blood glucose levels ≥7.8mmol/l2 hours after ingestion of the glucose solutionand none had glucose levels ≥11.1mmol/l. There was no consistency in the peaking of glucose levels within the two hours.i.e. subjects had their blood glucose levels peaking either at 30minutes, 60 minutes, 90 minutes or 120 minutes after consumption of the glucose solution as shown in graph 1 in the appendix.
The oral glucose tolerance test is usually used for the diagnosis of any type of diabetes at all stages with the exception of the earliest stages. According to the results obtained the alternative hypothesis is true given all the subjects had increased blood glucose levels 2 hours after ingestion of the glucose solution.All subjects appeared normal at zero minutes given their blood glucose levels were equal to or below the baseline i.e. ≤6.1mmol/l according to the 1999 WHO diabetes criteria-table 2-. However only one of the subjects had a baseline of 6.5mmol/l, this can be described as impaired fasting glycaemia (IFG) according to WHO criteria. Impaired fasting glycaemia is at times referred to as a pre-diabetic state associated with insulin resistance and if not controlled might lead to type 2 diabetes. On the other hand, 14 of the subjects had blood glucose levels above 7.8mmol/l 2 hours after ingestion of glucose solution; these subjects could therefore have an indication of impaired glucose tolerance (IGT). IGT arises due to dysglycaemia a result of insulin resistance in most cases and is also a pre-diabetic state and if not controlled might lead to diabetes and cardiovascular pathology. None of the subjects had blood glucose levels above 11.1mmol/l hence none was diabetic.
Definition, diagnosis and classification of diabetes mellitus and its complications. (1999). World Health Organization and International Diabetes Federation. Geneva.
Tekks. (2010). glycolysis diagram. wikipedia.
Wild S, R. G. (2004). Global prevalence of diabetes: estimates for 2000 and projections for 2030. Pubmed , 1047–53.