Birth Control Injections May Increase Risk for Type 2 in Women Who Have Had Gestational Diabetes

---

Long-acting injectable progestin contraception and risk of type 2 diabetes in Latino women with prior gestational diabetes mellitus, by A.H. Xiang and colleagues. Diabetes Care 29:613–617, 2006.

What is the problem and what is known about it so far?

Pregnant women who have never had diabetes before but who have high blood glucose levels during pregnancy are said to have gestational diabetes.

Women who've had gestational diabetes have a high risk of getting type 2 diabetes after giving birth. Additional pregnancies increase this risk, and getting pregnant while having mild, symptom-less diabetes doubles the risk of birth defects.

Why did the researchers do this particular study?

The researchers wanted to see if taking an injectable form of birth control affects the risk for getting type 2 diabetes in women who've had gestational diabetes.

The researchers looked at a type of birth control known as DMPA. DMPA contains progestin, which is similar to the hormone progesterone, which is naturally made by the female body. DMPA is given by injection into a muscle every 12 weeks and is slowly absorbed into the bloodstream to prevent pregnancy.

Who was studied?

A total of 526 Hispanic women who had gestational diabetes. The women gave birth between 1986 and 1997. None of them had diabetes when they had their check-up after giving birth.

How was the study done?

After giving birth, 96 women chose to use DMPA as their birth control and 430 women chose to take birth control pills. The women received check-ups about once a year for over nine years.

What did the researchers find?

The rate of diabetes was higher in the group who took DMPA than in the group who took birth control pills. The DMPA group had higher weight, a higher percentage of women who breast-fed, a higher frequency of family history of diabetes, and higher levels of fats in the blood when the study started; these differences may have accounted for much of the difference in diabetes risk.

Women who gained weight while using DMPA appeared to have a higher risk for getting diabetes.

Women who used DMPA, had high triglyceride levels (a type of fat in the blood) when the study began, and breast-fed their babies had an increased risk for getting diabetes.

What were the limitations of the study?

The women who took DMPA were at a higher risk for diabetes when the study started. They weighed more and had a more frequent family history of diabetes. They also gained more weight and had higher triglyceride levels and lower HDL cholesterol levels ("the good cholesterol"). All of these things increased their risk for getting diabetes. In addition, there were only 96 women in the DMPA group, compared with 430 in the birth control pill group.

What are the implications of the study?

Women who choose to use DMPA after having gestational diabetes should carefully monitor their blood glucose levels, especially if they have high triglyceride levels or choose to breast-feed their babies. More studies are needed to fully understand the effects of DMPA in women who've had gestational diabetes.

FOR MORE INFORMATION

Gestational Diabetes

Hormonal Birth Control: A Gestational Diabetes Risk?

Gestational Diabetes: What to Expect