The Effect of Steroids on Maternal Glucose Levels

Few studies have examined the effects on maternal glucose levels from corticosteroids, which are given during some complicated pregnancies to enhance fetal lung maturity when early delivery is expected. The applicability of these studies is limited by the presence of confounding factors and low numbers of participants (ranging between 7 and 50). Two relevant studies are by Mastrobiattista at al and Gurbuz et al. These studies had 7 and 40 subjects respectively, and studied the change in maternal 1-hour glucose tolerance tests following administration of steroids for fetal lung maturity. The 1-hour tests involve a standard oral glucose challenge and are used to screen for gestational diabetes; thus, they may not reflect the changes in circulating glucose levels from typical sources of glucose (such as meals) anticipated with steroid administration. Both studies showed a change in the results of glucose tolerance testing and concluded that screening for gestational diabetes should be delayed at least 72 hours to 1 week after completion of the steroid course. Neither study looked at maternal glucose values within the first 48 hours of giving the first dose of steroids, and neither addressed whether diabetes could be diagnosed alternatively by the maternal glucose response within the first 48 hours following steroid administration.

It has been the investigator's clinical observation that glucose values may be highest during those first 48 hours. Another study looked at the effect of various doses of insulin on the degree of hyperglycemia for the first 3 days following steroid administration and showed increases in glucose values even in the insulin-treated. Unfortunately, some subjects in that study had concurrent treatment with another agent known to cause hyperglycemia.

No standards of care exist to guide whether to monitor glucose values after steroid administration for fetal lung maturity. The time course of glucose elevations is not clear, and how often the glucose elevations reach a level that would generally warrant treatment is unknown. When glucose monitoring is performed, no standard exists to guide the duration or frequency of monitoring.

Detecting maternal hyperglycemia is important for several reasons, including:

1. High maternal glucose levels lead to high fetal levels and prompt a fetal response to the high glucose levels. Some of the pregnancies may go on to deliver while the maternal glucose levels are still high, resulting in a higher risk of neonatal hypoglycemia in the nursery and an increased risk of acidosis and injury in the brain if periods of distress occur during labor. By the nature of the clinical situations, most fetuses born in the first few days following administration of steroids will also be preterm and possibly already have additional factors which put them at risk for complications in labor and the nursery, so the hyperglycemia compounds the risk for them.
2. The maternal hyperglycemia may complicate the maternal course at a time when the pregnant woman is receiving other medications to control her premature labor or obstetric condition that prompted the use of the steroids in the first place. Fluid balance and constitutional symptoms may be affected by high glucose values. Rarely, diabetic ketoacidosis may be precipitated in someone with no history of diabetes.