OBJECTIVE: We aimed to 1) describe the peripartum management of type 1 diabetes at an Australian teaching hospital and 2) discuss factors influencing the apparent transient insulin independence postpartum.
RESEARCH DESIGN AND METHODS: We conducted a retrospective review of women with type 1 diabetes delivering singleton pregnancies from 2005-2010. Information was collected regarding demographics, medical history, peripartum management and outcome and breastfeeding. To detect a difference in time to first postpartum blood glucose level (BGL) of >8mmol/L between women with an early (<4hour) and late (>12hour) requirement for insulin postpartum, with a power of 80% and a type 1 error of 0.05, at least 24 patients were required.
RESULTS: An intravenous insulin infusion was commenced in almost 95% of women. Univariate analysis showed that increased body mass index at term, lower creatinine at term, longer duration from last dose of long- or intermediate-acting insulin and discontinuation of an insulin infusion postpartum were associated with a shorter time to first requirement of insulin postpartum (p=0.005, 0.026, 0.026 and <0.001,respectively). There was a correlation between higher doses of insulin commenced postpartum and number of out-of-range BGLs [r(36)=0.358, p =0.030) and hypoglycaemia [r(36)=0.434, p =0.007). Almost 60% had at least one BGL <3.5mmol/L between delivery and discharge.
CONCLUSIONS: Changes in the pharmacodynamic profile of insulin may contribute to the transient insulin independence sometimes observed postpartum in type 1 diabetes. A dose of 50-60% of the pre-pregnancy insulin requirement resulted in the lowest rate of hypoglycaemia and glucose excursions. These results require validation in a larger, prospective study.