Hormonal Contraceptives Pose Low Risk in Women With Diabetes

Miriam E Tucker

December 05, 2016

The risk of thromboembolic events from most hormonal contraceptives for women with diabetes is elevated but still relatively low, new research finds.

The results, from a large US claims database, were published online November 29 in Diabetes Care by Sarah H O'Brien, MD, of Nationwide Children's Hospital, in Columbus, Ohio, and colleagues.

Among nearly 150,000 women of childbearing age with diabetes using any hormonal contraceptive, the overall absolute risk for thromboembolic events was about one per 100 woman-years of use, with even lower rates seen for intrauterine and implantable subdermal contraceptives.

These two "highly effective" modalities "are excellent options for women with diabetes who hope to avoid the teratogenic effects of hyperglycemia by carefully planning their pregnancies," Dr O'Brien and colleagues write.

Concern has been raised about the risk of thromboembolic events from combined hormonal contraceptives among women with diabetes in particular, since diabetes itself also predisposes to such events.

The World Health Organization recommends that progestin-only contraceptives be prescribed for women with diabetes and other cardiovascular risk factors, but few prior data had been available for progestin-only contraceptives in women with diabetes.

"This gap in evidence may be contributing to lower rates of contraceptive counseling, prescriptions, or services for women with diabetes as compared with women without a chronic medical condition," Dr O'Brien and colleagues note.

Contraceptives Raise Thromboembolism Risk, but Overall Rates Are Low

Data on contraceptive use and thromboembolic events (venous thrombosis, stroke, or myocardial infarction) were initially analyzed from the Clinformatic Data Mart during 2002–2011 for 146,080 women aged 14 to 44 years with both type 1 and type 2 diabetes. The data were adjusted for age, smoking, obesity, and other cardiovascular risk factors, along with diabetes complications and cancer history.

Nearly three-quarters of the women (72%) had no claims for hormonal contraceptives during the study period.

About a quarter (24%) were dispensed estrogen-containing contraception, and 1.5% were dispensed both estrogen-containing and progestin-only contraception. Most of these women had gaps in coverage, leaving only 4% (6042) who received continuous use.

Just 4% (5987) had been dispensed progestin-only contraception, including depot medroxyprogesterone acetate (DMPA), a subdermal implant, or an intrauterine device (IUD). Of those, just 0.5% (680) had continuous use.

A total of 3012 thrombotic events occurred overall, for a total rate of 6.3 events per 1000 woman-years.

Highest rates were for those using a transdermal contraceptive patch (16.4/1000) and lowest for IUDs (3.4/1000) and subdermal implants (0/1000).

Compared with no hormonal contraception, estrogen-containing products significantly raised the risk for thromboembolism both in women younger than 35 years and 35 years and older (hazard ratios [HRs], 3.38 and 1.79, respectively; both P < .0001).

For progestin-only products, the risk was elevated only among the younger women (HR,2.02; P < .0001) and not those aged 35 and older (HR, 1.33; P = .059).

In a direct comparison, the thromboembolism risk was much lower with progestin-only than for estrogen-containing contraceptives, reaching statistical significance in women younger than 35 (HR, 0.60) but not older (HR, 0.74).

IUDs and Implantable Subdermal Contraceptives Are Good Options

No differences were found in thromboembolism risk between estrogen dose above or below 30 µg ("ultra-low-dose"), or between pills containing drospirenone or desogestrel/gestodene vs other types of progestin.

While there was a modestly increased risk of thromboembolism with the transdermal patch compared with oral contraceptives (HR, 1.68; P = .0091) no differences were seen for the vaginal ring.

Compared with women using an IUD, both progestin-only pills and DMPA were associated with about a fourfold increased thrombosis risk (HR, 3.69 and 4.69, respectively; both P < .0001). Nonetheless, the absolute risks were still low, at 14.5 and 12.5 per 1000 woman-years, respectively.

Only 124 women had been prescribed subdermal implantable progestin-only devices (Implanon and Nexplanon, Merck) and none had experienced a thrombotic event.

"Currently, diabetes affects around two million US women of reproductive age," note the authors, but "even among women with 'uncomplicated' diabetes — less than 20 years' duration and no end-organ disease — it appears that clinicians may avoid combined hormonal contraceptives because of concerns of cardiovascular side effects.

"Our results demonstrate the safety of hormonal contraception use in women with type 1 and type 2 diabetes. The contraceptives with the lowest absolute risk were the IUD and implantable subdermal contraceptives, and these highly effective reversible contraceptives are excellent options for women with diabetes," they conclude.

The study was funded by the American Diabetes Association. The authors report no relevant financial relationships.

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Diabetes Care. Published online November 29, 2016. Abstract

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