Ground breaking study shows gestational diabetes link to heart disease

17 January 2018

New research shows that women who get gestational diabetes are at a higher risk of getting type 2 diabetes, hypertension and ischaemic heart disease.

The study drew on data from more than 9,000 women in the UK who had been diagnosed with gestational diabetes mellitus (GDM) between January 1990 and May 2016.  This data was compared with that of more than 37,000 women who were the same age and pregnant over a similar time period but who did not develop GDM.

The research was carried out at the University of Birmingham and the lead author is Dr Barbara Daly from the University of Auckland’s School of Nursing who now hopes to carry out a similar study in New Zealand.

Gestational diabetes is increasing due to the obesity epidemic and increasing maternal age.

The study compared long-term cardiometabolic outcomes between the two groups of women.  Their mean age at the time of delivery was 33 years and ranged from 14 to 47 years.

A significantly greater proportion of women with GDM were economically deprived, overweight with a BMI of over 25, and had been diagnosed with hypertension.

“This was the first large population-based study in the UK that reports on the increased risk of cardiovascular disease in women diagnosed with GDM, and quantifies the high incidence of type 2 diabetes and hypertension in the post-partum period,” Dr Daly says.

Of the women diagnosed with GDM:

  • 3.2% developed hypertension compared with 1.3% of women in the control group
  • 0.2% ischaemic heart disease (IHD) 0.06 percent of control women.

“Women diagnosed with GDM were over 20 times more likely to develop type 2 diabetes, had almost twice the risk of developing hypertension and were two-and-half times more likely to develop ischaemic heart disease following delivery compared with control women.”

The increased risk persisted throughout the 25-year follow-up period. Follow-up screening for type 2 diabetes was poor with less than 60 percent of women with GDM undergoing screening in the early post-partum period and had decreased to less than 40 percent by the second year.

“The guideline recommendations for screening and management of hypertension, lipids and smoking cessation are lacking and need to be reviewed.”

Dr Daly says guidelines need to be adapted to recommend annual screening for type 2 diabetes and for major cardiovascular risk factors such as smoking, hypertension, cholesterol levels and in physical activity. Clinical guidelines need to include post-partum screening and management of all cardiovascular risk factors in women diagnosed with GDM - not limited to type 2 diabetes.

This study is the first UK and the largest population-based study of women with GDM that used primary care records to report on the incidence of cardiovascular disease without requiring a hospital admission. 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.

The findings are broadly consistent with a French study using hospital records, a Canadian study using primary care records and the US Nurses’ Health Study using self-reported diagnosis of GDM. However, because this is a new area of research, additional follow-up studies are required to further validate the current findings.

“It would be ideal to explore this relationship in New Zealand given our high rates of GDM and cardiovascular disease,” Dr Daly says.

The study findings, “Gestational diabetes and cardiovascular disease”, have been published in PLOS Medicine.