Obese women may increase their risk for developing type 2 diabetes by using the birth control shot marketed as Depo-Provera, according to a study by researchers at the Keck School of Medicine of USC.
The first to examine the drug’s effect on obese women, the study suggests that other forms of long-term birth control, namely intrauterine contraception, may be a more effective choice for overweight women.
“Obese women have a higher risk of developing type 2 diabetes and other cardiovascular diseases. They also have an increased risk for pregnancy complications,” said Penina Segall-Gutierrez, assistant professor of clinical obstetrics and gynecology, and family medicine at the Keck School. “We don’t want to prescribe a contraceptive that will push these women from borderline hyperglycemic to diabetic.”
Segall-Gutierrez led the study, which appeared in the January issue of the journal Contraception.
Depot medroxyprogesterone acetate (DMPA) is a progestin-only contraceptive that is administered by injection every three months. DMPA and other progestin-only methods are the only hormonal contraceptives recommended by the American Congress of Obstetricians and Gynecologists for obese women older than 35. Because most oral contraceptives increase the risk for developing blood clots, they are not recommended for obese women, who are more susceptible to clots than women of normal weight.
For the study, researchers compared the insulin sensitivity, body mass index, blood sugar and cholesterol levels of 15 women (five of normal weight and 10 who were overweight) before injection and 18 weeks after. The participants, recruited over a seven-month period at the Women’s and Children’s Hospital of the Los Angeles County+USC Medical Center, received an injection of DMPA upon acceptance into the study and another 12 weeks later.
The researchers found that both normal-weight and obese women became more insulin resistant after receiving DMPA, which means that their bodies became less effective at lowering blood sugars. However, it appeared that the normal-weight women were able to compensate by producing more insulin. The data suggested that weight gain, an increase in insulin resistance, or both play a role in the increased susceptibility for diabetes among obese women who use DMPA.
Future research should observe effects over a longer period of time and compare how obese women using nonhormonal contraception fare to those using DMPA, Segall-Gutierrez said. Despite the small sample studied, she said the results are useful for clinicians who counsel obese women about contraception.
“Depo is used by 6 percent of American women, but it’s more popular than the intrauterine device or implant,” she explained. “These are other forms of contraception that don’t increase one’s risk for diabetes.”
Co-authors included Keck School researchers Anny H. Xiang, Richard M. Watanabe, Enrique Trigo, Frank Z. Stanczyk, Xinwen Liu, Ronna Jurow and Thomas A. Buchanan. The research was funded by an anonymous donor.
University of Southern California