Basic Concepts in Clinical Biochemistry-A Practical Guide.7z

15.6 Calculations

Plot a graph between amount of glucose at x-axis and absorbance at y-axis. Extrap-
olate glucose amount of the given sample from the graph or calculate using the
equation below:

Plasma glucose¼

ODof testamount of standard mgðÞ 100

ODof standardvolume of sample mlðÞ

¼xmg=dl

15.7 Clinical Significance...............................

In normal persons, the fasting blood glucose level is within 70–110 mg/dl. Follow-
ing oral intake of glucose, the level rises and reaches at peak within 1 h and then
come to normal fasting levels within 1.5–2 h because of insulin secretion and
utilization and storage of glucose. After 2 h it should be below 120 mg/dl. There
should be a negative test for glucose in all urine samples. In diabetes mellitus, the
glucose tolerance is decreased. The glucose level increases to much higher levels
after 1 h of glucose intake and does not reach normal level even after 2 h due to low
insulin level or decreased cellular response toward insulin. In impaired glucose
tolerance, the blood sugar values are below diabetic level but above normal
(Fig.15.1). In renal glycosuria, the glucose tolerance is normal; however glucose
will appear in urine.

Fig. 15.1 Glucose tolerance test curve

66 15 To Perform Glucose Tolerance Test