*This lab involves working with human blood. You should handle your own blood. All materials
that come into contact with blood need to be disposed of properly. Sharp objects that come into
contact with blood need to be disposed of in the biohazardous sharps container. Other material
(ie. cotton gauze, paper towels, alcohol wipes, etc) need to be disposed of in the biohazardous
container. All body fluids and supplies must be treated as potentially infectious.
INTRODUCTION:
Insulin is a hormone produced and secreted by the beta cells of the islets of Langerhans in the
pancreas. Its principal function is to assist the transport of glucose across the cellular membrane.
When insulin is lacking or deficient, amount of glucose available for cellular respiration becomes
limited. Inhibiting glucose transport results in accumulation of glucose in the blood, resulting in
a condition known as hyperglycemia. Normal blood glucose concentration is considered to be
90 mg% (90 mg / 100 ml of blood), but may often range between 60 mg% to 140 mg%. Excess
insulin causes decrease in blood glucose levels, leading to a condition called hypoglycemia.
Diabetes mellitus (often just “diabetes) can be due to lack of insulin production or defective
responsiveness to insulin, and causes hyperglycemia. Symptoms of hyperglycemia include
glucosuria (urinary excretion of glucose in urine), polyuria (increased urination due to
increased osmolarity of urine), polydipsia (excessive thirst due to increased loss of water), and
polyphagia (increased hunger). When cells do not have enough glucose for energy, the cells
compensate by increasing their metabolism of fats and proteins. The increased metabolism of
fats releases into the blood large quantities of ketone bodies, which are intermediates of fat
metabolism. These are excreted in urine and have the easily recognizable odor of acetone. Also,
ketone bodies are acidic and their accumulation will cause a drop in blood pH (acidosis). Severe
acidosis can lead to coma and death.
Glucose Tolerance Test
The glucose tolerance test assesses the body’s ability to respond to excess ingestion of glucose.
Ability to handle excess glucose is markedly different between a normal and diabetic person.
This difference is shown in Figure 1. In the normal person, the blood glucose level rises from
about 90 mg% to around 140 mg% in 1 hour and then falls back to normal within 3 hours.
Glucose level may even drop below normal due to excess insulin release. The diabetic person
shows a hyperglycemic response, in which the blood glucose level rises from about 120 mg% to
160 mg% to as high as 300 mg%, and then slowly falls to the fasting diabetic level after a
prolonged period of about 5 – 6 hours. The diabetics abnormal response is caused by the
inability of the pancreas to secrete additional insulin in response to elevated blood glucose.
PROCEDURE:

1. Select one person from each team to report to the lab in the fasted state (not having eaten
   for the last 12-18 hours). For our purpose, it may be adequate if the student just skips one
   meal preceding the lab.
2. Determine each subject’s normal blood glucose level by using the Accu-Chek glucose
   test (the instructor should explain usage of this method ahead of time). When obtaining
   blood for this test, clean the finger with 70% isopropyl alcohol first and use a sterile
   lancet.
3. Each volunteer will then drink a lemon-flavored solution that contains 10g glucose per
   ounce (1 ounce = 29.6 ml). Quantity of solution will be based on the following: 1 gram
   of glucose per kilogram of body weight.
4. After ingesting the glucose drink, the subject will repeat the blood glucose test every 30
   minutes for 2 hours.
5. Record and graph the data for all groups. Then compare/analyze the results.
   DATA TABLE:
   Time 0 min 30 min 60 min 90 min 120 min
   Student 1
   Student 2
   Student 3
   Student 4
   Student 5
   Figure 1
   GRAPH:
   QUESTIONS:
6. How are levels of insulin and glucagon regulated in the body?
7. What causes the “insulin shock” seen when an overdose of insulin is given to an
   organism?
8. Why is there an increase in urine output (polyuria) in diabetics?
9. What can cause the urine of diabetics to be acidic?
10. What is the cause of polyphagia in diabetics?
11. Some diabetics control their blood glucose by ingesting tablets rather than by receiving
    injections of insulin. How do these tablets work, and who may use them?
12. Define the following terms:
    Glycogenesis:
    Glycogenolysis:
    Gluconeogenesis:
    Ketosis:
    Ketoacidosis: