Author: Eleanor McDermid
medwireNews: Impaired glucose tolerance during pregnancy that does not meet the criteria for gestational diabetes nevertheless increases the likelihood that women will later develop type 2 diabetes, a study shows.
“As pregnancy serves as a window of opportunity for increasing health awareness and adopting a favourable lifestyle, women with gestational glucose intolerance below the threshold for gestational diabetes should be informed of their potential short-term and long-term health risks,” say Gilad Twig (Sheba Medical Center, Ramat-Gan, Israel) and co-researchers.
Their study involved 177,241 women who were tested for gestational diabetes, 1262 of whom were diagnosed with type 2 diabetes during a median 10.8 years of follow-up.
The incidence of type 2 diabetes was 2.6 per 10,000 person–years among the 83.5% of women who had normal glucose tolerance during pregnancy. This increased to 8.9 per 10,000 person–years for the 8% with an abnormal glucose challenge test but normal oral glucose tolerance test (OGTT), and 26.1 per 10,000 person–years for the 4% of women who had one abnormal OGTT value.
Women with gestational diabetes (4.5%; at least two abnormal OGTT values) had a type 2 diabetes incidence of 71.9 per 10,000 person–years.
The differences between the glucose intolerant groups and women with normoglycemia were statistically significant after accounting for factors such as age, education, socioeconomic status, pre-pregnancy BMI, and BMI during adolescence.
Looking in more detail at the women’s OGTT results, the researchers found that type 2 diabetes risk increased with the number of abnormal values, from one to four.
They also discovered a particularly high diabetes risk in women who had an abnormal pre-load OGTT measurement, ie, abnormal fasting glucose. For example, the diabetes risk for women with gestational diabetes was elevated 38.02-fold above those with normoglycemia in women with impaired fasting glucose but by 12.24-fold in those without.
Moreover, women whose only OGTT abnormality was impaired fasting glucose had an 11.81-fold increased risk relative to those with normoglycemia.
The research is published in The Lancet Diabetes & Endocrinology along with a commentary from David Simmons (Western Sydney University, New South Wales, Australia) and Arianne Sweeting (The University of Sydney).
They write: “Along with the high progression rates to type 2 diabetes, these data confirm that preventative lifestyle programmes, or potentially metformin treatment, might be needed beyond women with gestational diabetes to include women with even one elevated glucose value.”
The commentators also highlight the impact of impaired fasting glucose on future diabetes risk, saying that “along with the known high rates of nausea and vomiting with the 100 g glucose load and the ethnic variation in glucose profile on the OGTT,” the findings raise “important questions over the consistency, validity, and patient-centredness” of current approaches to diagnosing gestational diabetes.
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