Gestational diabetes mellitus: antenatal variables as predictors of postpartum glucose intolerance

To determine whether antepartum variables can predict postpartum glucose intolerance.

Glucose tolerance was assessed 6 weeks postpartum in 94 of 238 women with gestational diabetes using a 2-hour, 75-g oral glucose tolerance test (GTT). Selected antepartum variables were analyzed for predictive ability for postpartum glucose intolerance.

Of 238 patients, 94 (39%) returned for a GTT. Those returning and those not returning were similar in all variables. Postpartum glucose intolerance occurred in 34%: impaired glucose tolerance in 18%, overt diabetes in 16%. No single maternal, intrapartum, or neonatal variable was predictive of postpartum glucose intolerance in all cases. Predictive variables included: requirement for insulin (insulin versus diet: 25 versus 3% impaired glucose tolerance, 26 versus 0% diabetes; P = .001), poor glycemic control (any 2-hour postprandial blood sugar level of 150 mg/dL or higher: 34 versus 5% diabetes; P = .005), and the 50-g GTT value (200 mg/dL or higher: 32 versus 6% diabetes; P = .01). For insulin requirement, the relative risk (RR) was 17.28 (95% confidence interval [CI] 2.46-121.45), and for the above three variables combined, the RR was 19.68 (95% CI 2.88-134.2). When the insulin dose was at least 100 U/day, all patients had abnormal glucose tolerance postpartum (RR = 34.00, 95% CI 4.93-234.39).

Postpartum glucose screening is not warranted for women at low risk who do not require insulin during pregnancy. The incidence of postpartum glucose intolerance in this group is very low. Women with risk factors should receive postpartum screening. Patients receiving at least 100 U/day of insulin have a 100% incidence of postpartum glucose intolerance.