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Adverse Outcomes Up with High A1c in Late Pregnancy for Type 1 Women

An HbA1c of 6.5-6.9% at 26 weeks’ gestation correlated with significantly elevated risk of preterm delivery, preeclampsia, need for neonatal glucose infusion, and a composite adverse outcome…

Michael J.A. Maresh, M.D., from St. Mary’s Hospital in Manchester, U.K., and colleagues conducted a prospective assessment involving 725 women with type 1 diabetes to examine the correlation between second and third trimester glycemic control and pregnancy outcomes. The women were categorized into five groups according to hemoglobin A1c (HbA1c) values at 26 and 34 weeks’ gestation, with the lowest value of

The researchers found that an HbA1c of 6.0 to 6.4 percent at 26 weeks’ gestation correlated with increased risk of large for gestational age (odds ratio, 1.7) children. An HbA1c of 6.5 to 6.9 percent at 26 weeks’ gestation correlated with significantly elevated risk of preterm delivery, preeclampsia, need for neonatal glucose infusion, and a composite adverse outcome (odds ratios, 2.5, 4.3, 2.9, and 3.2, respectively). There was a progressive increase in these risks with increasing HbA1c. Similar results were seen at 34 weeks’ gestation. Less consistent trends were seen for the glucose profile.

The researchers concluded that a continuous relationship was shown between multiple maternal and neonatal adverse outcomes and increasing A1C values in the second and third trimester of pregnancy in women with type 1 diabetes. These adverse outcomes were significantly associated with HbA1C of ≥6.5% (48mmol/mol) and LGA with an HbA1C ≥6.0% (42mmol/mol). They asserted that women should be advised to aim for target values of <6.5% (48mmol/mol) and ideally <6.0% (42mmol/mol) if this is possible without excessive hypoglycemia. If this goal is not achieved, additional surveillance by experienced clinicians is indicated. While capillary blood glucose data were generally concordant with the A1C results, it was not possible to define a clear target range. However, third trimester pre-prandial glucose values between 6.0- 6.9mmol/l were associated with an increased risk of an adverse composite neonatal outcome, which supports the current ADA and NICE guidelines of

“The data suggest that there is clinical utility in regular measurement of HbA1c during pregnancy,” the authors write.

Practice Pearls:

  • Elevated HbA1c during the second and third trimesters correlates with increased risk of adverse pregnancy outcomes.
  • An HbA1c of 6.0 to 6.4 percent at 26 weeks’ gestation correlated with increased risk of large for gestational age.
  • An HbA1c of 6.5 to 6.9 percent at 26 weeks’ gestation correlated with significantly elevated risk of preterm delivery, preeclampsia, need for neonatal glucose infusion, and a composite adverse outcome.

Published online before print November 3, 2014, doi: 10.2337/dc14-1755 Diabetes Care November 3, 2014 Abstract