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Gestational Diabetes Screening GESTATIONAL DIABETES SCREENING Glucose

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                    GESTATIONAL DIABETES SCREENING
In 2006 Colorado Clinical Guidelines Collaborative produced Gestational Diabetes
Guidelines. Integrated within this section, are those guidelines. The notation “CO
CCG” will be added to recommendations that may be in addition to the guidelines
already in the section. An effort was made to include all the essential content; however
we recommend Colorado practitioners review the website for exact documents at:
http://www.coloradoguidelines.org/guidelines/diabetes/gestationaldiabetes/gestationaldiabetes.h
tm.
Screening
       Screening for glucose intolerance is usually accomplished by testing all patients
       at 24-28 weeks gestation. Alternatively, testing can be performed on selected
       high-risk patients.
Why Screen
          Older studies show that patients with gestational diabetes mellitus (GDM)
           have higher fetal/infant morbidity-mortality than patients with normal glucose
           values.
          Recent studies of GDM patients managed with dietary control and intensive
           maternal-fetal surveillance have demonstrated a maternal-fetal perinatal
           mortality equal to the patients who do not have the diagnosis of GDM.
          Women diagnosed with GDM are at increased risk for hypertension,
           preeclampsia, and cesarean delivery. Infants are at increased risk for
           macrosomia and shoulder dystocia.
Risk Factors for GDM
       The following have been associated with a significant increase in the incidence of
       GDM:
          maternal age > 30
          unexplained stillbirth
          family history of DM
          neonatal death due to trauma
          previous infant > 4000g
          prior history of GDM
          obesity (wt >180 lbs) BMI > 29kg/m2)
          hypertension
          recurrent moniliasis
          persistent glycosuria
          macrosomia by ultrasound
          polyhydramnios
          smoking
          non-white ethnicity
      Additional discussion is found in Section C3 Gestational Diabetes Mellitus
      (GDM), page 279.00.
      CO CCG: age > 35 years, polycystic ovary disease, history of GDM related OB
      complications.
      The most sensitive factors are age greater than 30, family or personal history of
      diabetes, obesity, and glycosuria.
Criteria for Determining Low-Risk Status
      These patients require no glucose testing, but this category is limited to those
      women meeting ALL of the following characteristics:(3)
         age < 25 years
         weight normal before pregnancy (BMI of 25 or less)
         member of an ethnic group with a low prevalence of GDM
         no known diabetes in 1st-degree relatives
         no history of abnormal glucose intolerance
         no history of poor obstetric outcome
      CO CCG: If a woman does not have any risk factors, screening should be
      performed between 24 and 28 weeks. If the woman has risk factors, screening
      should be performed at the 1st prenatal encounter and then possibly again at 24-
      28 weeks. It is suggested that screening for GDM be universal. However, you
      may opt not to test only if the woman is less than 25 years of age, BMI< 26kg/m2,
      Caucasian, no known diabetes in a 1st -degree relative, no history of abnormal
      glucose testing, and has no history of poor obstetric outcome.
Timing of Test
      Both the timing of test and the specific tests used should be discussed with your
      consultant as there are several acceptable times and methods. In general,
      patients without any risk factors are screened between 24 and 28 weeks with a
      1-hour O'Sullivan test. Patients with the above risk factors should be screened at
      their 1st prenatal visit. If this early screen is normal, repeat the screen at 24-28
      weeks. Those patients with an abnormal O'Sullivan screen require a 3-hour oral
      glucose tolerance test.
      Glycosuria or LGA appearing in pregnancy should lead to consideration for
      repeat testing even if the patient has had a previous normal 1-hour test.
      If a patient has a fasting plasma glucose level > 126 mg/dl (7.0 mmol/L) or a
      casual plasma glucose > 200 mg/dl (11.1 mmol/L), she meets the threshold for
      the diagnosis of diabetes. If these values are confirmed on a subsequent day,
      this precludes the need for any glucose challenge.
How to Test
      The patient drinks a 50 gram glucose load (Glucola) without regard to time of
      day or time of last meal. Plasma glucose is drawn 1 hour following the 50 gram
      load. The patient should be instructed to avoid eating, drinking, chewing gum or
     smoking in the hour between the consumption of the glucose and the drawing of
     the blood.
     If a patient has trouble tolerating the glucose load (e.g., vomits), consider some
     of the following:
        Sip the glucose slowly over 5 minutes rather than all at once.
        Dilute it to no more than 25 grams/100ml. Lowering the concentration of the
         glucose in the beverage lowers the osmolality of the solution, producing less
         nausea.
        Serve it cold. Warm, sugary drinks may produce more nausea than cold drinks.
        Replace the 50 gm glucose beverage with 28 jelly beans (Brach No. 110 Jelly
         Beans, EJ Brach Manufacturing, Chicago, IL). This has been shown to be an
         equivalent source of sugar with fewer side effects.(6)
Gestational Normal Values
     The recommended normal plasma (not whole blood) level of a 1-hour Glucola
     test is less than 140mg%. If the screen is normal, no further testing is needed
     unless the test was done prior to 24 weeks gestation. It is important to know
     whether your laboratory is using blood or plasma glucose. Whole blood levels
     are 15% lower than plasma levels. Please consult your laboratory for method of
     testing and adjust your values accordingly. Due to the above, it is practical to
     use a laboratory and to avoid this test in the office laboratory.
     Some providers use a value of 135mg%. Using this lower value will increase
     your sensitivity from 80 to 90%. ACOG states that either threshold is acceptable.
Abnormal Screen
     Any patient with an abnormal 1-hour glucose screen requires further testing.
     This is accomplished with a 3-hour oral glucose tolerance test. The 3-hour test is
     done following a 3-day carbohydrate loading diet (150 gm/day) and 8-12 hour
     fast the night before. It consists of a 100 gm oral glucose challenge after a
     fasting plasma glucose determination.
     Glucose values are then drawn at 1-hour intervals for a total of 3 hours. Normal
     values are listed below. Gestational diabetes is diagnosed if 2 or more of your
     patient's values are equal to or greater than the established norms. There are
     several cut-off values used to determine glucose intolerance. The 2 most
     popular, Carpenter/Coustan and the National Diabetes Data Group are shown
     below. There is no data to support one scale being superior over the other.
     Each practice can elect which scale to utilize.
     Management of these patients is discussed in Section C3 Glucose Intolerance,
     page 278.00. There may be significant risk for patients with only one abnormal
     value, but at this time no clinical management is recommended. LGA has been
     associated with poor glucose control and one abnormal 3-hour value.
                                                            National Diabetes
         Blood Draw Time      Carpenter / Coustan
                                                               Data Group
                                                       Venous Plasma (mg/dL)

       Fasting                                 95                                105

       1 hour                                 180                                190

       2 hour                                 155                                165

       3 hour                                 140                                145

Postpartum Gestational Diabetes
      Approximately 97.5% of patients with GDM revert to normal glycemia when
      tested at 6 weeks. Postpartum testing at 6 weeks is recommended to confirm
      resolution of GDM and identify women with Type I or II diabetes. This test is
      usually done with a 75 gm oral glucose load performed on a non-fasted
      individual. The plasma glucose at 2-hour post glucose load should be 200 mg/dl
      or less to be normal. Alternatively, a fasting glucose of 140 mg/dl or less equals
      normoglycemia and the patient should be so advised. Plan this by entering to
      the Hospital area 33, of the Flow Sheet: postpartum DM screen.
Treatment
      See Section C3 Gestational Diabetes Mellitus (GDM) in Pregnancy, page 278.00
      or C3 Diabetes Mellitus (DM) in Pregnancy, page 283.00 of this manual.
Preplan
      Program this test by circling the appropriate green box or boxes on line 10 of the
      Flow Sheet. Enter N or A to document normal or abnormal result. If the patient
      has a normal screen prior to 24 weeks, generally it is recommended to repeat the
      screen at 24-28 weeks. Circle the green box to plan this re-exam.
Patient Education
      Distribute the pink patient education sheet to patients who will be screened.
      There is a sheet for the 1-hour (10B) as well as a sheet for the 3-hour (10C) test.
Risk Factor
      If the screen is abnormal, enter this to area 31 of the Flow Sheet: gestational
      diabetes.
References
      1. Creasy RK, Resnik R, Iams J (eds): Maternal-Fetal Medicine Principles & Practice. Ch 49
         Diabetes in Pregnancy. 5th edition, Philadelphia. WB Saunders Co, 2003.
      2. York R, et al: Diabetes Mellitus in Preg: Clinical Review. J of Perinatology, (3):285-93, Sep 1990.
      3. American Diabetes Association: Clinical Practice Recommendations 2000. Gestational
         Diabetes Mellitus, Volume 23; Supplement 1.
      4. ACOG: Practice Bulletin, Number 30, September 2001.
      5. Winter WE, Schatz DA: Performing an Oral Glucose Tolerance Test in a Pregnant Woman
         with Severe Emesis. Medscape Diabetes & Endocrinology 5(1), 2003.
      6. Lanear ME, Kuehl TJ, Cooney AT, et al: Jelly beans as an alternative to a fifty gram glucose
         beverage for gestational diabetes screening. Am J Obstet Gynecol, 181:1154-1157, 1999.
      7. Colorado Collaborative Clinical Guidelines. Gestational Diabetes Guidelines 2006.
          http://www.coloradoguidelines.org/guidelines/diabetes/gestationaldiabetes/gestationa
          ldiabetes.htm
Special Instructions

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