Use of insulin glargine during pregnancy: a case-control pilot study

Objective To determine whether the use of insulin glargine during pregnancy is associated with an increase in the incidence of fetal macrosomia or adverse neonatal outcome. Design A matched case-control study. Setting Women's Centre, John Radcliffe Hospital, Oxford, UK. Sample Sixty-four pregnant women treated with insulin during their pregnancies, 20 with type I diabetes and 44 with gestational diabetes. Methods Two groups of women were compared in matched pairs. A study group of 32 pregnant women with diabetes treated with insulin glargine during their pregnancy and a control group of 32 pregnant women treated with an intermediate-acting human insulin (isophane or insulin zinc suspension) and matched for weight at booking, height, gestation at delivery, parity, fetal sex, duration of insulin use in pregnancy and glycaemic control during the third trimester of pregnancy (glycosylated haemoglobin [HbA(1c)] concentration and mean blood glucose concentration). Main outcome measures Birthweight, centile birthweight, the incidence of fetal macrosomia (birthweight > 90th percentile) and neonatal morbidity in the two study groups. Results There was no significant difference between the birthweight or centile birthweight of babies born to the women treated with insulin glargine during pregnancy and that of the babies born to those in the control group treated with intermediate-acting human insulin. The overall incidence of fetal macrosomia was 12/32 (37.5%) in the insulin glargine group and 13/32 (40.6%) in the control group. There was no significant difference in neonatal morbidity between the groups. Conclusions The results of this pilot study indicate that insulin glargine treatment during pregnancy does not appear to be associated with increased fetal macrosomia or neonatal morbidity.