Study finds injectable and oral birth control do not adversely affect glucose and insulin levels

Fasting glucose and insulin levels remain within normal range for women using injectable or oral contraception, with only slight increases among women using depot medroxyprogesterone acetate (DMPA), commonly known as the birth control shot, according to new research from the University of Texas Medical Branch (UTMB Health) in Galveston.

The study, published in the January 2011 issue of Obstetrics and Gynecology and conducted over three years, is the largest to measure fasting glucose and insulin levels among women using DMPA, oral (desogestrel) contraception and non-hormonal (bilateral tubal ligation, condom or abstinence) methods. Researchers found that DMPA users' glucose levels increased steadily during the first 30 months of use, with the greatest increase occurring during the first six months. The observed increases, which were less than those reported in previous studies, were not significant enough to cause concern.

There are 62 million women of reproductive age in the United States. More than two million American women use DMPA, including approximately 400,000 teens, and more than 11 million use oral contraception.

"Previous studies were limited in scope and offered conflicting results, which led physicians to question whether hormonal contraception could lead to diabetes," says lead author Dr. Abbey Berenson, professor, Department of Obstetrics and Gynecology and director of the Center for Interdisciplinary Research in Women's Health. "Further studies are needed to determine how women with diabetes are affected by DMPA and oral contraception, but these results are reassuring for non-diabetic women already receiving the shot or on the pill."

A Body of Research on the Effects of Contraception

The findings are the fourth in a series of UTMB Health studies published in Obstetrics and Gynecology that add to the growing literature enabling physicians to better counsel women accurately about the positive and adverse side effects associated with widely used forms of contraception.

Other studies included in the series examined the effect of contraception on weight gain and bone density loss. All of the studies followed a sample of 703 African-American, Hispanic and white women between the ages of 16 -33 years-old from 2001 through 2004 who chose their own contraception method. Researchers also examined such variables as: race and ethnicity, age, parity, duration of use, previous use of contraceptive method, lifestyle behaviors like diet, smoking, drinking and physical exercise, and socioeconomic status.

Findings include:

Contraception and Bone Loss

In a study published in January 2010, Berenson and UTMB Health co-author Dr. Mahbubur Rahman, assistant professor, Department of Obstetrics and Gynecology and Center for Interdisciplinary Research in Women's Health, examined the relationship between contraception and bone mineral density (BMD) loss. They found: