CHICAGO, IL -- Aug. 11, 1998 --The incidence of contracting type II diabetes following a prior case of gestational diabetes, while already high, is increased nearly three times more in women using progestin-only contraceptives, according to an article in tomorrow’s issue of The Journal of the American Medical Association.

Siri Kjos, M.D., and colleagues from the University of Southern California School of Medicine in Los Angeles examined the rate of development of type II diabetes mellitus in a group of 904 Latina women who had recently experienced gestational diabetes mellitus. The authors found that women who had chosen to use progestin-only contraceptives while breast-feeding nearly tripled their risk of contracting type II diabetes, compared to the other women in the study.

Although low-dose hormonal contraceptives appear to be safe for the general population, the researchers questioned its safety in this high-risk group (women who experience gestational diabetes are already three times more likely to develop diabetes than the average population).

"Altogether, 169 of the 904 study subjects developed diabetes during follow-up, giving an overall average incidence rate of 9.9 percent per year," the researchers write.

The rate for women who chose non-hormonal contraceptives was 8.7 percent compared to 11.7 percent for those who chose an oral contraceptive. The rate for women using progestin-only oral contraceptives was 26.5 percent.

Uncontrolled diabetes increases the risk of birth defects, miscarriages and many other potentially life-threatening complications during pregnancy, therefore effective contraception can be essential for these high-risk patients. The patients in the study who chose to use oral contraceptives while continuing to breast-feed were all prescribed a progestin-only contraceptive, because the hormone levels in combination hormone contraceptives can adversely affect milk production.

Other breast-feeding mothers in the study chose non-hormonal/non-pharmaceutical methods of birth control. This group experienced the same rate of development of diabetes, as did the other women in the overall study group who also chose non-hormonal methods.

"Non-hormonal methods are associated with a lower risk of developing diabetes during breast-feeding and are preferable in that setting," the researchers write, suggesting that if progestin-only oral contraceptives are prescribed at all, they should be accompanied by careful monitoring of blood glucose concentrations of high-risk women.

Nearly half of the overall study group chose non-hormonal methods of birth control. According to the researchers, approximately 97 percent of the women attending the high-risk family planning clinic studied have Spanish surnames and were born in Mexico or Central America.

"Oral contraceptives are available in the United States in two general forms: progestin-only and combination estrogen-progestin oral contraceptives," the researchers explained. "While the metabolic effects of individual preparations vary, the impact of currently available progestin-only and low-dose combination oral contraceptives on glucose tolerance in the general population has been minimal.

"Therefore, low-dose oral contraceptives are generally prescribed without concern about precipitation of hyperglycemia, and clinical monitoring of glucose levels is not recommended in healthy women."

The researchers conclude that this study of Latino women with prior gestational diabetes did not reveal a significant increase in the risk of developing type II diabetes during long-term use of low-dose progestin and estrogen combination contraceptives compared with the use of non-hormonal contraception.

"By contrast, use of a progestin-only oral contraceptive preparation during breast-feeding was associated with nearly a three-fold increase in the risk of diabetes," they write.

The researchers add that progestin-only oral contraceptives should probably be prescribed with caution, if at all, in these high-risk women.

Thanks to The Doctor's Guide to the Internet™ for the article