Ten-year experience of insulin treatment in gestational diabetes

Between 1975-1984, 119 women with gestational diabetes (GDM) were treated with insulin in Uppsala, representing a mean yearly incidence of 4.5/1,000 pregnancies. Women with GDM were older and more obese than the general pregnant population. Insulin treatment was instituted during a 5-7 day stay in hospital. The mean total daily dose of insulin prepartum, when fasting blood glucose had been normalized, was 53 (SD +/- 25) units (34 +/- 15 units of rapid-acting and 20 +/- 11 units of medium-acting insulin), divided into two doses daily. Mean duration of treatment was 6.4 weeks. The perinatal mortality was 0.8%, compared with 7.4% in previous pregnancies in the same women. The perinatal morbidity was generally mild and included hypoglycaemia (10.9%), hyperbilirubinaemia requiring treatment (2.5%), shoulder dystocia (2.5%) and one case of mild respiratory distress syndrome. The rate of macrosomia was reduced in the present pregnancies compared with previous ones in the women with GDM, but not abolished completely, probably because of too short a duration of improved metabolic control. Spontaneous delivery was favoured and the rate of Caesarean section was 13.5%. Thus, treatment with high doses of insulin in an unselected group of women with GDM is feasible. Normal perinatal mortality, reduced macrosomia, and no gross perinatal morbidity was found in the infants. Though the extent to which insulin treatment per se contributed to the favourable outcome is difficult to assess, it is suggested that the case for a high level of ambition for metabolic normalization in GDM should be a subject of further study.