GDM increases long term risk for type 2 diabetes

Women with gestational diabetes are at a higher risk of developing type 2 diabetes for more than 20 years after pregnancy. Whereas the risk for type 1 diabetes reduces after seven years.

These are the results of a new Finnish study.

The prevalence of gestational diabetes mellitus (GDM) and type 2 diabetes is increasing worldwide. A number of studies have shown that women with GDM are at high risk of developing diabetes later in life.

About the study

In this latest study, out of Finland, researchers worked with 391 women who delivered a baby between 1984 and 1994.

This included 363 women who were diagnosed with gestational diabetes through an oral glucose tolerance test (OGTT) and 28 who were treated with insulin.

The women were matched by age, parity and date of delivery with a control group.

The women were asked to participate in a questionnaire in 1995 and 1996, between 1 and 11 years after their pregnancy.

The questions included details about their GDM treatment, pre-pregnancy weight and height, progression to diabetes, time of diagnosis and medication.

A follow-up questionnaire was conducted  in 2012 and 2013, when a total of 297 women with gestational diabetes and 297 matched controls participated.

The results

In the follow-up period, more than half of the women in the gestational diabetes group went on to develop either type 1 (5.7%) or type 2 (50.4%) diabetes.

All the type 1 diabetes diagnoses occurred within 7 years of pregnancy, whereas type 2 diabetes diagnoses increased through the end of the study. A period of 20 years.

Only 5.5% of women in the control group developed type 2 diabetes, and none developed type 1 diabetes.

For the 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 a 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 48 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 Of these women, 46% developed type 2 diabetes and 27% developed type 1 diabetes.

Impact of insulin therapy

Participants who received insulin therapy for their GDM diabetes had greater odds of receiving a diagnosis of type 1 or type 2 diabetes than those who did not receive insulin.

For women  who were diagnosed with type 1 diabetes, only 1.2% did not have insulin therapy for their gestational diabetes. The sensitivity of insulin therapy to predict type 1 diabetes was 90.5% and for type 2 diabetes was 56.9%.

The time to a diabetes diagnosis was also longer for women who were not treated with insulin.

Monitoring after pregnancy essential

The researchers said that 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. However, the risk for type 2 diabetes remained and warranted an individualized, lifelong follow-up.

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