Target Patients With Gestational Diabetes After Birth to Reduce Risks

Marlene Busko

January 23, 2018

In a UK cohort of pregnant women, those with gestational diabetes had a greater risk of developing type 2 diabetes, hypertension, and ischemic heart disease than other women, but no increased risk of stroke, over a 3-year follow-up[1].  

However, only about 60% of the women with gestational diabetes had a check-up a year later that included screening for type 2 diabetes (as recommended).

And few women with or without gestational diabetes received 1-year screening for other CVD risk factors such as high body mass index (BMI), hypertension, dyslipidemia, and smoking.  

"The findings report on a large population and identify an at-risk group of relatively young women ideally suited for targeting of risk factor management to improve long-term metabolic and cardiovascular outcomes," say Dr Barbara Daly (University of Auckland, New Zealand), and colleagues, in their article published January 16 in PLoS Medicine.

"Clinical guidelines should include postpartum screening and management for all cardiovascular risk factors in women diagnosed with [gestational diabetes] and not restrict it to [type 2] diabetes," they stress.

Clinicians and women with gestational diabetes should be aware of these increased risks, and clinicians should establish a recall system (for example, through electronic medical records) to ensure these women are assessed for cardiovascular risk each year. 

Only Three Prior Studies on Gestational Diabetes and Long-term CVD

Gestational diabetes is increasing because of the obesity epidemic and older pregnant mothers, Daly and colleagues note, and it is well established that gestational diabetes greatly increases the lifetime risk of type 2 diabetes.

The UK National Institute for Health and Care Excellence (NICE) guidelines recommend screening women with gestational diabetes for type 2 diabetes between 6 and 13 weeks postpartum, measuring HbA1c levels each year, and making changes in diet and exercise to maintain a healthy weight.  

However, NICE guidelines don't specify that women with gestational diabetes should be screened postpartum for other CVD risk factors.

And to the best of their knowledge, Daly and colleagues note, only three studies have reported on the link between gestational diabetes and long-term risk of CVD.  

These studies of cohorts in Ontario[2], France[3], and North America (North American Nurses' Health Study II)[4] found that patients with gestational diabetes had an increased risk of CVD during a follow-up of 7 to 26 years.    

Still, "there are now sufficient studies that strongly link gestational diabetes to cardiovascular disease," senior author Dr Krishnarajah Nirantharakumar (Institute of Applied Health Research, University of Birmingham, UK) told theheart.org | Medscape Cardiology in an email.

Nirantharakumar acknowledged, however, that the mechanisms to explain this remain to be elucidated in further research.

Of Those With Gestational Diabetes, 1 in 10 Developed Type 2 Diabetes

For the current work, researchers conducted a retrospective cohort study using The Health Improvement Network (THIN), a nationally representative database of women seen in primary care practices in the United Kingdom. They identified 9118 women who became pregnant during 1990 to 2016 and were diagnosed with gestational diabetes.

They matched these women with 37 281 women of the same age who became pregnant around the same time but did not develop gestational diabetes, to identify the risk of developing coronary artery disease (CAD) that did not require hospitalization.

The women were a median age of 33 years (range, 14–47) and were followed for a median of 2.9 years (up to 25 years).  

Women who developed gestational diabetes were more likely to have an economically deprived background, be overweight or obese (BMI ≥25 kg/m2; 63% vs 35% of normal weight women) or have hypertension, but were less likely to be current smokers (16% vs 19%). 

During follow-up, about 1 in 10 women with gestational diabetes (9.8%) vs only 0.38% of other women developed type 2 diabetes.

Women with gestational diabetes were also more likely than other women to develop CAD (0.15% vs 0.06%, respectively) or hypertension (3.2% vs 1.3%, respectively).

After adjusting for confounders, gestational diabetes was associated with a 21-fold higher risk of developing type 2 diabetes, and about a 2- to 3-fold higher risk of developing hypertension or CAD, but no increased risk of stroke.

Risk of Developing CVD Risk Factor, Women With vs Without Gestational Diabetes*

CVD Risk Factor IRR P
Type 2 diabetes 21.96** <0.001
Hypertension 1.85** <0.001
CAD 2.78*** 0.005
Stroke or TIA 0.96*** 0.87
IRR = incidence rate ratio; TIA = transient ischemic attack
*During a median follow-up of 2.9 years postpartum
**Adjusted for economic deprivation, BMI, and smoking
***Also adjusted for economic deprivation, BMI, smoking, lipid-lowering medication, and hypertension
 

The risk for type 2 diabetes was greatest in the first year following delivery but persisted for 25 years.

Only 58% of the women with gestational diabetes had a test for glycemia at 1 year, which dropped to less than 40% at 2 years postpartum.

The researchers acknowledge that a study limitation was the short follow-up, so few women developed CVD.

Nevertheless, their findings are in broad agreement with those from the three prior trials, they say.

"The findings add an important insight into the trajectory of the development of type 2 diabetes, hypertension, and cardiovascular disease in the early and latter post-partum periods," Daly and colleagues note.

And "while the value of preventing cardiovascular outcomes requires further studies," there is some evidence that targeting the subgroup of young women with gestational diabetes for prevention programs "may yield benefits in reducing conversion to type 2 diabetes," they conclude.  

The authors have reported no relevant financial relationships.

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