Women diagnosed with gestational diabetes have an increased risk of developing diabetes mellitus in the future. The risk is highest in women who needed insulin treatment, had antibodies associated with diabetes (such as antibodies against glutamate decarboxylase, islet cell antibodies and/or insulinoma antigen-2), women with more than two previous pregnancies, and women who were obese (in order of importance).[60][61] Women requiring insulin to manage gestational diabetes have a 50% risk of developing diabetes within the next five years.[40] Depending on the population studied, the diagnostic criteria and the length of follow-up, the risk can vary enormously.[62] The risk appears to be highest in the first 5 years, reaching a plateau thereafter.[62] One of the longest studies followed a group of women from Boston, Massachusetts; half of them developed diabetes after 6 years, and more than 70% had diabetes after 28 years.[62] In a retrospective study in Navajo women, the risk of diabetes after GDM was estimated to be 50 to 70% after 11 years.[63] Another study found a risk of diabetes after GDM of more than 25% after 15 years.[64] In populations with a low risk for type 2 diabetes, in lean subjects and in women with auto-antibodies, there is a higher rate of women developing type 1 diabetes.[61]