medwireNews: Research suggests that women with gestational diabetes who have elevated glycated haemoglobin (HbA1c) levels in the third trimester of pregnancy should be closely monitored for the development of diabetes after delivery.
Although HbA1c had poor sensitivity, missing around eight in 10 cases, it was a highly specific predictor, the researchers report in Primary Diabetes Care.
The average third trimester HbA1c level was 5.5% in 73 women from the prospective Mamma Study who were diagnosed with diabetes within 5 years after delivery, compared with 5.0% in 63 who developed prediabetes and 4.9% in 60 who remained normoglycaemic.
The most specific HbA1c cutoff was 6.5%; all 10 women with this level or higher developed diabetes, making it 100% specific, while a cutoff of 5.7% had a specificity of 96.7%.
However, the corresponding sensitivities were just 13.7% and 30.1%, report Rickard Claesson (Lund University, Malmö, Sweden) and study co-authors.
A much lower HbA1c threshold of 5.1% was 71.2% sensitive, but had a reduced specificity of just 61.7%.
Nevertheless, the researchers say: “These data provide evidence to suggest there may be a useful HbA1c threshold above which all women should be closely monitored, starting already during pregnancy, to prevent diabetes development after delivery.”
Although stressing that HbA1c is not a suitable screening tool in this instance, because of the low sensitivity, they say “it could be used as a strategy for selecting high-risk women for lifestyle interventions to prevent diabetes”.
They also recommend it because it “can be performed without fasting, and is more reproducible and less cumbersome than an oral glucose tolerance test”.
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