The use of glucose-lowering medications for the treatment of type 2 diabetes mellitus during pregnancy in the United States

Introduction Some guidelines allow for the use of either insulin or noninsulin antidiabetic agents for gestational diabetes, but only insulin is recommended for pregnant women with preexisting type 2 diabetes mellitus (T2DM). We aimed to document treatment patterns in routine care for women with preexisting T2DM. Methods We identified pregnancy cohorts within 2 US claims databases for publicly and privately insured individuals: the Medicaid Analytical eXtract (2000-2014) and OptumClinformatics (2004-2014). T2DM was classified with a validated algorithm using ICD-9-CM and CPT codes. We assessed medication usage over the years of the study, and changes in medication use before and after the beginning of pregnancy, using prescription fills as a proxy for the use of insulin, metformin, sulphonylureas and other noninsulin antidiabetic agents before pregnancy and during each trimester. Results Among 12,631 women with T2DM, insulin use in pregnancy was stable over the study years (55%-60% in the 2nd trimester), but 2nd trimester use of metformin increased from <5% to 20%. Over the study period, 41% of women filled a prescription for metformin before pregnancy, 37% in the 1st trimester and 17% in the 2nd trimester. By the 2nd trimester, few women used sulphonylureas (11%) or other noninsulin antidiabetic agents (1%). Of the women on metformin only before pregnancy, 36% switched to insulin only by 2nd trimester, 11% added insulin and 16% continued on metformin only. Of the women on metformin and insulin before pregnancy, 61% switched to insulin only by 2nd trimester, 22% continued with metformin and insulin and <5% used only metformin. Conclusion The use of insulin-metformin combinations and other noninsulin antidiabetic drugs during pregnancy has increased. Safety studies for these medication regimens are needed.