The study is being done in order to gain information on the most suitable types of birth control in women who recently had gestational diabetes, or diabetes diagnosed during pregnancy. The intrauterine device (IUD) is a highly effective form of birth control. It is inserted into the uterus and prevents pregnancy for either 5 or 10 years, depending on the type of IUD (hormone-releasing or copper). The hormone-releasing IUD works for 5 years and releases a hormone called a progestin into the uterus. The copper IUD contains no hormones and works for 10 years. The IUD is an excellent form of birth control postpartum, but it is unknown if the hormone-releasing IUD will affect blood sugars and increase a woman's risk of becoming diabetic when she's not pregnant. The hypothesis is that the hormone-containing IUD will NOT increase blood sugars, so women who use the hormone-containing IUD will have similar blood sugars to those who use the copper IUD or have had their tubes tied (no hormones).

Inclusion Criteria:

1. Age 18-45 years at the time of enrollment
2. Single gestation in the current pregnancy
3. GDM in the current pregnancy, diagnosed by 2- or 3-hour oral glucose tolerance test (OGTT) performed at 24-32 weeks gestation
4. Desires intrauterine contraception or tubal ligation postpartum
5. Willing and able to read and sign an informed consent form in English
6. Willing to comply with the study protocol

Exclusion Criteria:

1. History of pre-gestational DM, type 1 or 2
2. Pregnancy conceived with assisted reproductive technologies
3. Positive for human immunodeficiency virus (HIV) infection
4. Desires repeat pregnancy within the first 12 months following delivery

Postpartum women with gestational diabetes in the last pregnancy