Effect of antenatal betamethasone on blood glucose levels in women with and without diabetes

Objective: To characterize the maternal glycemic response to betamethasone in subjects without diabetes compared to subjects with diabetes.

Study design: Blood glucose levels in 22 gravidae without diabetes and 11 gravidae with diabetes were recorded for 48h following betamethasone administration for threatened preterm delivery. Maximum blood glucose value and time to maximum value were compared. Area under the curve calculations were used to express the duration and degree of significant hyperglycemia for individual subjects. These summary measures were then correlated to subject characteristics and laboratory values to determine a risk profile of those subjects without diabetes at risk for significant hyperglycemia.

Results: All subjects with diabetes and the majority of those without diabetes had significant hyperglycemia during the study period. Mean maximum blood glucose was higher for those with diabetes (205mg/dL vs. 173mg/dL, p⩽0.01). Mean time to reach the maximum glucose level was similar for both groups. Result of a glucose tolerance test given immediately prior to betamethasone correlated strongly with amount of time spent with hyperglycemia for subjects without diabetes (rho=0.59, p⩽0.01). Morbidly obese subjects spent less time with hyperglycemia than those with lower body mass indices (p=0.03).

Conclusion: Both subjects with and without diabetes demonstrate significant hyperglycemia after receipt of antenatal betamethasone.