Impact of Antenatal Betamethasone on Plasma Glucose Levels
Condition: Hyperglycemia
MeSH terms: Hyperglycemia
Study type: Observational

Summary: 
      It is known that administration of steroids increases blood sugar levels. Administration of
      betamethasone is common practice during pregnancy to women at risk for preterm delivery.
      However, it is unknown the magnitude of the changes in glucose these women have after
      receiving betamethasone. The purpose of this study is to determine the magnitude and timing
      of the increase in blood sugar in pregnant women without diabetes who receive steroids.
    

Detailed description: 
      There is a substantial body of evidence that the administration of corticosteroids to
      patients deemed to be at risk for preterm delivery (delivery prior to 37 weeks gestation)
      decreases the risk of respiratory distress syndrome, intraventricular hemorrhage, and
      neonatal death. Current recommendations from the National Institute of Health (NIH) and the
      American College of Obstetricians and Gynecologists (ACOG) are that patients with pregnancies
      that are between 24-34 weeks gestation deemed at risk for preterm delivery receive antenatal
      corticosteroids. The recommended dosing is two doses of betamethasone 12 mg given 24 hours
      apart as an intramuscular injection. (Alternatively, dexamethasone 6 mg given intramuscularly
      every 6 hours for 4 doses may be administered. Betamethasone is used preferentially in our
      institution.)

      Glucocortiocoids have a well-known effect on glucose metabolism. They increase blood glucose
      levels by antagonizing insulin and decreasing synthesis of insulin, thus inhibiting
      peripheral glucose utilization and increasing gluconeogenesis (the process by which the body
      produces glucose). Pregnancy is also characterized by a relative insulin resistance that
      results in glucose intolerance. It follows, then, that the combination of pregnancy and
      corticosteroids could cause significant disruption of glucose homeostasis.

      Routinely in pregnancy, gestational diabetes is diagnosed by the administration of a glucose
      tolerance test consisting of ingestion of 50g of glucose followed by a serum glucose level
      one hour later. This is known as a one-hour post-glucola test. A value of 140 mg/dL is
      considered abnormal, and prompts administration of the 3-hour glucose tolerance test. This
      test consists of a fasting blood sugar, followed by serum glucose levels after a 100g oral
      glucose challenge at 1-, 2- and 3-hours. A profile with two or more abnormal values is
      considered diagnostic for gestational diabetes. In 1997 Fisher et al retrospectively compared
      the incidence of gestational diabetes in those patients who had received tocolytics and
      antenatal corticosteroids to those who did not, and found a higher incidence of both abnormal
      one-hour glucose screening tests and gestational diabetes in those patients who received
      steroids and tocolytics (medications used to try to decrease uterine contractions). However,
      the interval between the receipt of steroids and the administration of the glucose screening
      test was quite variable in this study. Shelton et al in 2002 evaluated the extent of
      hyperglycemia in non-diabetic patients who received multiple weekly doses of corticosteroids.
      They found that the fasting glucose levels increased for several days following the first
      course of steroids, returned to normal, and then remained persistently elevated in those
      patients who received three or more courses. Postprandial levels were not significantly
      altered. A study by Gurbuz et al in 2003 assessed the effects of betamethasone on the
      one-hour glucola test and found that although there was an initial effect on the screening
      test, this effect was transient and resolved generally one week after the administration of
      the second dose of betamethasone. These patients had a one-hour screening test performed
      prior to the administration of corticosteroids. The dosing regimen of betamethasone, however,
      was different from that recommended by ACOG. Thus far, no study has reported if: (1) there is
      significant hyperglycemia in non-diabetic patients who receive corticosteroids and (2) how
      the magnitude and pattern of the increase in glucose differs in patients with normal and
      abnormal one-hour glucolas or with diabetes. This study will be conducted as a pilot study,
      as there is no reports of the extent of hyperglycemia that occurs in non-diabetic patients
      after administration of corticosteroids to guide a sample size calculation. We will plan to
      obtain thirty non-diabetic subjects with fifteen diet-controlled diabetic controls for
      comparison. The hypothesis is that those patients that are not diabetic will not have the
      same extent of hyperglycemia as those who are diabetic.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Pregnant women receiving corticosteroids