(B02) Adherence to hypoglycemic medications among pregnant patients with gestational diabetes

Publication Number: 614

Background: Gestational diabetes mellitus (GDM) is a common pregnancy complication, often requiring hypoglycemic medications to control blood glucose and prevent adverse perinatal outcomes. Hypoglycemic medications have different administration methods, side-effect profiles, and prescribing complexity. Few studies have characterized medication adherence for GDM in pregnancy.

Objectives: To examine adherence to different hypoglycemic medications among pregnant patients with GDM.

Methods: We constructed a retrospective cohort of pregnant patients enrolled in Tennessee (TN) Medicaid who delivered between 2007-2019 using enrollment files, insurance claims, and pharmacy data linked to vital records and a state hospitalization registry. We included patients with a diagnosis of GDM whose initial prescription was either metformin, glyburide, or insulin. We excluded patients who switched or added additional hypoglycemic medications to their original regimen, and those who started treatment < 30 days before delivery. Adherence was defined as the proportion of days covered between treatment initiation and delivery. We used multivariable linear regression to examine the association (beta [95% Confidence Interval]) between hypoglycemic medications (using insulin as reference) and adherence, adjusting for a-priori selected covariates. In secondary analyses, we stratified estimates by state region, rurality, race, and non-English speaking status.

Results: Of 4387 patients meeting eligibility criteria, medication type varied (insulin 29%, metformin 30%, glyburide 41%). Overall adherence was high (median 89%, IQR 69-100%), with highest adherence to glyburide (median 91%, IQR 71-100%). Compared to insulin, metformin was associated with significantly lower adherence (-2.2 [-4.03,-0.47]), but glyburide was not (1.16 [-0.58, 2.90]). In analyses stratified by region, patients in west TN had lower adherence to metformin and glyburide compared with insulin (-9.52 [-14.22,-4.81] and -5.28 [-8.98,-1.58] respectively), but this was not observed in patients in middle or east TN. Among Black patients, metformin was significantly associated with lower adherence compared to insulin (-6.19; [-9.90, -2.48]), but this was not observed in white or Hispanic patients. Among non-English speaking patients, glyburide was associated with higher adherence compared to insulin (9.58 [1.84, 17.33]).

Conclusions: Adherence to hypoglycemic medications varied among pregnant patients with GDM by state region, race, and non-English speaking status. Further investigation into adherence patterns among pregnant patients in different clinical settings is warranted.