2.11: Glucose Tolerance Test
- Page ID
- 38639
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)RELATED READING: Chapter 32. See Methods in CD-ROM for Glucose.
OBJECTIVES
Upon completion of this exercise, appropriate discussion, and related reading, the student will be able to:
- Explain how to perform a Glucose Tolerance Test (GTT) for Gestational Diabetes.
- Construct a graph showing the relationship of time to serum glucose concentration.
- Perform calculations that allow evaluation of a glucose tolerance test.
- Discuss the possible physiological status of the patient that would produce the observed results.
- Determine urine glucose concentrations (Optional).
PROCEDURE
- Perform glucose determinations on the patient samples provided using the procedure given in the previous exercise (#10). Each student will have GTT samples from one patient drawn at the following intervals: fasting, 60 min., 120 min., 180 min. The determination of urine glucose levels is an optional activity. Your instructor will give you specific instructions dealing with that procedure.
- Perform glucose determinations on the urine samples provided with your GTT samples and record the results on the data sheet (optional).
- Plot the results of serum glucose (mg/L, Y or vertical axis) vs. time (hours, X or horizontal axis) to establish a Glucose Tolerance Curve. Using the discussion of the O’Sullivan-Mahan test (as modified by Carpenter-Coustan) in Chapter 32 determine if the patient has gestational diabetes. The test uses a 100-g glucose load. Cut-off criteria for a normal response to this test are: fasting 950 mg/L, 1-hour 1800 mg/L, 2-hour 1550 mg/L, 3-hour 1400 mg/L. Two or more of the plasma glucose values must be equaled or exceeded for a diagnosis of gestational diabetes.
| DATA SHEET, EXERCISE #11 |
NAME: ___________ DATE: ___________ |
| Absorb. 525 nm | Calculated Glucose Value (mg/L) | Target Glucose Value (mg/L) | Urine Glucose (Optional) (mg/L) | Exceeds limits? | |
|---|---|---|---|---|---|
| Standard | |||||
| Normal Control | |||||
| Abnormal Control | |||||
| Fasting | |||||
| 1 Hr. | |||||
| 2 Hr. | |||||
| 3 Hr. |
Discussion Questions
- What do the results of your glucose values, the O’Sullivan-Mahan test and graph suggest regarding this patient?
- Do the urine glucose values you obtained correspond to the serum values in the expected manner? Explain.
- What are the advantages and disadvantages of using a 3 hr. post-prandial evaluation instead of a 4 or 5 hour tolerance test?
