Fasting plasma glucose predicts adverse pregnancy outcome better than post-load glucose
medwireNews: Elevated fasting plasma glucose (FPG) is associated with a higher risk for babies born large‐for‐gestational‐age (LGA) and for hypertensive disorders of pregnancy (HDP) than elevated post‐load glucose in women with gestational diabetes, population-based study data show.
Furthermore, the associations persist despite treatment, which Edmond Ryan (University of Alberta, Edmonton, Canada) and co-investigators say “highlights the need for future research to examine whether fasting hyperglycaemia is a marker of some metabolic derangement that results in adverse outcomes in pregnancy.”
Among 257,547 pregnancies with live singleton births recorded in Alberta, Canada, between October 2008 and December 2014, 80.9% had negative 50‐g glucose challenge tests and 14.1% had negative 75‐g oral glucose tolerance tests (OGTT), indicating no gestational diabetes.
However, 5.0% had gestational diabetes according to the Diabetes Canada criteria, that is, either elevated FPG (≥5.3 mmol/L; 1.6%) or elevated 1‐h (≥10.6 mmol/L) and/or 2‐h (≥8.9 mmol/L) oral glucose tolerance test values (3.4%) on the 75-g OGTT.
Ryan and team report in Diabetic Medicine that women with elevated FPG had the highest rate of babies born LGA, at 22.4%, whereas the rate among women with elevated post-load glucose (9.1%) was closer to the rates among women with negative glucose challenge test pregnancies (8.1%) and those with a negative OGTT (11.0%).
A similar pattern was seen for HDP, with corresponding rates of 11.9%, 8.0%, 5.1%, and 7.0%.
After adjustment for maternal factors such as age, ethnicity, parity, and comorbidity, women with FPG were a significant 2.66 times more likely to have babies that were LGA and 1.51 times more likely to develop HDP than those with post‐load glucose elevations only.
The researchers also found that women with elevated FPG levels had the highest rates of cesarean section, induction of labor, adverse neonatal outcomes (shoulder dystocia, Erb’s palsy, or clavicle fracture), and preterm delivery, relative to those with elevated post‐load glucose levels, and those with no GDM.
In addition, the authors note that more women with GDM initiated pharmacologic treatment in the elevated FPG group than in the elevated post-load glucose group, at 31.4% versus 15.9%. Insulin monotherapy was the most common treatment given overall (91.2%), followed by metformin monotherapy (6.1%), and a combination of both insulin and metformin (2.6%).
In spite of this, “FPG remained significantly associated with adverse outcomes in gestational diabetes pregnancies with and without pharmacological intervention,” Ryan et al remark.
They add: “Whether an elevated FPG in pregnancy is attributable to a more severe insulin secretory defect or greater hepatic insulin resistance is unknown. It appears as if an elevated FPG in pregnancy may be a marker of some metabolic derangement that gives rise to LGA infants, one that is not necessarily corrected when the hyperglycaemia is treated.”
By Laura Cowen
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