Hormonal contraception is safer than expected for women with diabetes

The study, one of the first to evaluate hormonal contraception and health outcomes in women with a chronic condition, should encourage physicians to include implants and IUDs in birth control discussions with diabetic patients.

"Clinicians need to get beyond the idea that birth control just means 'the pill,'" said study senior author Eleanor Bimla Schwarz, professor of internal medicine at UC Davis Health System. "There are options that are safe and effective for all women, including those with diabetes."

Estrogen-containing birth control -- including oral contraceptives, transdermal patches and vaginal rings -- prevent pregnancy by suppressing ovulation. While effective contraceptives, these methods increase women's risks for heart attacks, strokes and blood clots. Physicians have been especially reluctant to prescribe hormonal birth control to women with diabetes, as adults with diabetes are two to four times more likely to die from heart disease than adults who do not have diabetes.

The study authors wanted to know to what extent the risks of cardiovascular events for diabetic women differed with various types of hormonal birth control. Using data from Clinformatics, a health claims database encompassing 15 million commercially-insured people throughout the U.S., they examined information from 2002 to 2011 on reproductive-aged females with type 1 or type 2 diabetes. The records of nearly 150,000 women were evaluated for hormonal birth control prescriptions and the occurrence of strokes, heart attacks or blood clots, also known as thromboembolism.

The outcomes showed that the vast majority of diabetic women -- 72 percent -- did not receive prescription contraception of any kind, even though pregnancy planning is critical for this population.

"This was alarming, since women with diabetes become pregnant as often as other women," said lead author Sarah O'Brien, associate professor with Nationwide Children's Hospital. "Pregnancy timing is critical for women with diabetes. It's best to carefully plan pregnancies and ensure that the diabetes is under good control, because high sugars can cause an increased chance of birth defects."

Overall, thromboembolic events among women in the study were low, with 6.3 events per 1,000 women each year. The contraceptives least likely to be associated with thrombosis were IUDs and subdermal implants. Estrogen patches and progestin-only injections were both associated with slightly increased risks of thromboembolism.

"The next step is to understand the best ways to share this information with women who have diabetes and make sure they are consistently offered a full range of contraceptive options," Schwarz said.

In addition to Schwarz and O'Brien, study contributors were Terah Koch of Nationwide Children's Hospital and Sarah Vesely of the University of Oklahoma Health Sciences Center. The study was funded by the American Diabetes Association.