medwireNews: Real-world data from Canada show that increasing maternal glycemia is associated with rising rates of large for gestational age (LGA) births, confirming the results of the landmark HAPO trial.
Furthermore, Padma Kaul and colleagues, from the University of Alberta in Edmonton, found that in women with post-load glucose levels above the threshold for gestational diabetes diagnosis and treatment, LGA rates were significantly lower in the current study than in HAPO.
They say this “provides clear presumptive demonstration of the effectiveness of [gestational diabetes] treatment in reducing LGA rates in the real-world.”
However, the researchers also note that the same pattern was not observed for fasting plasma glucose (FPG) even though this marker was “a stronger predictor of LGA than post-load glucose elevations.”
Therefore, “[p]rospective studies are needed to examine whether more aggressive treatment to lower glucose thresholds would impact LGA rates in pregnancies with elevated FPG,” write Kaul and co-authors in Diabetic Medicine.
The current study included data for 97,032 pregnancies recorded in Alberta between 2008 and 2018 that were categorized based on the results of 75 g oral glucose tolerance tests (OGTT) into the same seven groups as those used for the 23,316 pregnancies in the HAPO study.
At baseline, mean FPG was the same, at 4.5 mmol/L (81.2 mg/dL), in both the Alberta and HAPO cohorts, whereas mean 1-hour (8.8 vs 7.4 mmol/L; 158.6 vs 133.4 mg/dL) and 2–hour (7.4 vs 6.2 mmol/L; 133.4 vs 111.8 mg/dL) glucose values were significantly higher in the Alberta cohort.
The investigators found that for women in lower FPG categories, such as those below the threshold for gestational diabetes diagnosis (<5.3 mmol/L; 95.6 mg/dL), the rates of LGA births increased significantly with increasing FPG.
And the same was true for women with 1-hour and 2-hour glucose levels below the threshold for gestational diabetes diagnosis (9.6 and 8.8 mmol/L; 173.0 and 158.6 mg/dL, respectively).
In multivariate analyses adjusted for potential confounders, elevated FPG was associated with a significant 1.87-fold increased risk for an LGA outcome. This increased to 2.04-fold with elevated FPG plus one elevated post OGTT measure (either 1- or 2-hour) and 2.41-fold with elevated FPG and both post-load measures above the gestational diabetes diagnostic threshold.
Conversely, an elevated post-OGTT value without elevated FPG was associated with a significantly lower risk for LGA (odds ratio=0.81) relative to no post-load elevation.
Kaul and team say that this finding confirms “[t]he higher prognostic significance of FPG” compared with post-load glucose elevation and is in contrast to the HAPO data which found no single measure “to be superior in predicting LGA rates.”
The authors conclude that “[t]he HAPO study findings continue to be relevant in real-world clinical practice” but note that “FPG plays a more important role in identifying pregnancies at risk of LGA.”
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