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Disclosures: The authors report no relevant financial disclosures.
November 19, 2020
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Risk for type 2 diabetes remains more than 2 decades after gestational diabetes

Source/Disclosures
Disclosures: The authors report no relevant financial disclosures.
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The risk for type 2 diabetes remains high more than 2 decades after pregnancy for women with gestational diabetes, whereas the risk for type 1 diabetes subsides after 7 years, according to data from a 23-year follow-up study in Finland.

“The prevalence of gestational diabetes mellitus and type 2 diabetes is increasing worldwide, and studies have shown that women with gestational diabetes are at high risk of developing diabetes later in life,” Anna-Maaria Auvinen, resident physician at Oulu University Hospital in Finland, and colleagues wrote. “We previously reported a prospective, 6-year follow-up study of women with gestational diabetes and healthy control counterparts, showing that 4.6% of the gestational diabetes cohort developed type 1 diabetes and 5.3% developed type 2 diabetes, while none of the control group became diabetic. We report here the results of the 23-year follow-up study of these women.”

Researchers conducted a cohort study with 391 women with gestational diabetes and a single pregnancy who delivered a baby at Oulu University Hospital between 1984 and 1994. Women who were diagnosed with gestational diabetes through an oral glucose tolerance test (n = 363) or treated with insulin (n = 28) were included in the study. The women were matched by age, parity and date of delivery with a control group.

Participants were invited to participate in a questionnaire in 1995 and 1996, between 1 and 11 years after pregnancy. The women answered questions about their gestational diabetes treatment, prepregnancy weight and height, progression to diabetes, time of diagnosis and medication. A second follow-up questionnaire was distributed in 2012 and 2013, when a total of 297 women with gestational diabetes and 297 matched controls participated.

In the follow-up period, 53.2% of women in the gestational diabetes group developed type 1 (5.7%) or type 2 (50.4%) diabetes. All type 1 diabetes diagnoses occurred within 7 years of pregnancy, whereas type 2 diabetes diagnoses increased linearly through the end of the study. Only 5.5% of women in the control group developed type 2 diabetes, and no one developed type 1 diabetes.

For women who developed type 1 diabetes, the most predictive OGTT marker was a 2-hour glucose value at 11.9 mmol/L, which showed a sensitivity of 76.5% and specificity of 96%. For type 2 diabetes, the most predictive OGTT value was fasting glucose at a level of 5.1 mmol/L, which showed a sensitivity of 63.5% and specificity of 68.2%. Researchers analyzed a subgroup of women from the gestational diabetes cohort who had a fasting glucose of 7 mmol/L or higher or a 2-hour glucose of 11.1 mmol/L or higher during pregnancy (n = 48). In the subgroup, 46% developed type 2 diabetes and 27% developed type 1 diabetes.

Participants who received insulin therapy for gestational diabetes had greater odds of receiving a diagnosis of type 1 or type 2 diabetes than those who did not receive insulin. For those who were diagnosed with type 1 diabetes, only 1.2% did not have insulin therapy for gestational diabetes. The sensitivity of insulin therapy to predict type 1 diabetes was 90.5% and for type 2 diabetes was 56.9%. The diabetes diagnosis time was also longer for women who were not treated with insulin.

“Women with gestational diabetes, especially those on insulin treatment, should be carefully monitored for the first decade after the pregnancy, after which the risk for type 1 diabetes becomes negligible,” researchers wrote. “However, the risk for type 2 diabetes remains and warrants an individualized, lifelong follow-up.”