Exclusion of Women of Childbearing Potential in Clinical Trials of Type 2 Diabetes Medications: A Review of Protocol-Based Barriers to Enrollment

OBJECTIVE Women of childbearing potential are often excluded from participating in clinical trials owing to concerns about adverse fetal effects of treatment. This study aims to determine the prevalence of fertility-related exclusion criteria in clinical trials of type 2 diabetes medications and to determine whether these criteria are commensurate with drug risk. RESEARCH DESIGN AND METHODS ClinicalTrials.gov was queried for trials of type 2 diabetes medications that were phase 2 or 3, were based in the U.S., and enrolled participants 18-40 years old. Six hundred eighty-eight trials met criteria. Information collected about each trial included enrollment, trial length, exclusion and inclusion criteria, trial sponsor, and pregnancy category of drug(s) administered. RESULTS Most studies (59%) included one or more fertility-related exclusion criteria, most often excluding current pregnancy (55%) and breast-feeding (44%). Trials of medications with increased fetal risk were not more restrictive: trials of category C drugs (evidence of fetal risks in animals) were less likely to exclude pregnancy compared with trials of category B drugs (no known human or animal fetal risks) (45.6% vs. 69.8%, odds ratio [OR] 0.37 [95% CI 0.20, 0.65], P = 0.0005) or to require contraceptive use (29.9% vs. 57.1%, OR 0.32 [95% CI 0.18, 0.56], P = 0.001). CONCLUSIONS In clinical trials of type 2 diabetes medications, exclusion criteria affecting women of childbearing potential are often disproportionate to risk to the participant and fetus. These criteria have the potential to impede young women's access to clinical trials and may hinder the acquisition of clinical knowledge critical for improving the care of women with diabetes.