Women who suffer from high blood pressure during pregnancy are at an elevated risk of becoming diabetic in subsequent years, according to a Canadian study.
The findings, published on Tuesday in the online journal PLOS Medicine, could help doctors pinpoint women who need special medical attention. It may even be possible to prevent the diabetes before it starts with early interventions.
"I am hopeful that physicians will start to recognize this risk factor in their patients," said the study's lead author, Dr. Denice Feig, an adjunct scientist at the Institute for Clinical Evaluative Sciences in Toronto.
There are two blood-pressure-related conditions that can arise in pregnancy – gestational hypertension and the potentially more serious pre-eclampsia. Mild forms of pre-eclampsia are fairly common. But in severe cases, blood pressure skyrockets, which can be fatal for both mother and child. The pregnancy may need to be ended early by inducing labour.
Both gestational hypertension and pre-eclampsia are associated with insulin resistance – a prediabetic condition in which the body does not respond properly to insulin, the hormone that regulates blood sugar.
A few earlier studies have hinted that women with either of these two conditions may be prone to developing type 2 diabetes after their pregnancy. But the studies were small and far from conclusive.
So Feig and her research colleagues embarked on much larger study to settle the issue. They analyzed data from more than a million women who gave birth in Ontario from April, 1994, and March, 2008. Scanning through the medical records, the researchers looked for women who later developed type 2 diabetes. The maximum follow-up reached 16.5 years and the median follow-up was 8.5 years.
The study revealed that gestational hypertension and pre-eclampsia roughly double the risk of developing diabetes in the decade following pregnancy. Among women who did not have blood-pressure complications, 2.81 out of every 1,000 would be diagnosed with diabetes each year after pregnancy. But with women afflicted with gestational hypertension, the incidence rose to 5.26 per 1,000, and with those who had pre-eclampsia, it jumped to 6.47 per 1,000.
In separate article published with the study, Thach Tran from the University of Adelaide in Australia wrote that the findings are strong enough to justify a diabetes-screening program in women who suffered from blood-pressure complications during pregnancy.
Although researchers do not fully understand the underlying causes of gestational hypertension and pre-eclampsia, they do know that maintaining a healthy body weight, eating properly and getting regular exercise can help to prevent diabetes.
This is advice that everyone should follow, noted Feig, an endocrinologist at Mount Sinai Hospital and associate professor at the University of Toronto. "But if you knew you are at increased risk of developing diabetes, you may be more motivated" to adopt a healthy lifestyle, she said.