['Gestational diabetes mellitus (GDM) affects approximately 7-17\xa0% of all pregnancies and has been recognized as a significant risk factor to neonatal and maternal health. Postpartum, GDM significantly increases the likelihood of developing type 2 diabetes (T2D). While it is well established that insulin resistance and impaired β-cell function contribute to GDM development, the role of active β-cell loss remains unknown. Differentially methylated circulating free DNA (cfDNA) is a minimally invasive biomarker of β-cell loss in type 1 diabetes mellitus. Here we use cfDNA to examine the levels of β-cell death in women with GDM.', 'Second to third-trimester pregnant women with GDM were compared with women with normal pregnancy (PRG), women at postpartum (PP), and non-pregnant (NP) women. Fasting glucose levels, insulin, and C-peptide levels were measured. Serum samples were collected and cfDNA purified and bisulfite treated. Methylation-sensitive probes capable of differentiating between β-cell-derived DNA (demethylated) and non-β-cell-derived DNA (methylated) were used to measure the presence of β-cell loss in the blood.', 'GDM was associated with elevated fasting glucose levels (GDM\xa0=\xa0185.9\xa0±\xa05.0\xa0mg/dL) and reduced fasting insulin and c-peptide levels when compared with NP group. Interestingly, β-cell derived insulin DNA levels were significantly lower in women with GDM when compared with PRG, NP, and PP groups (demethylation index: PRG\xa0=\xa07.74\xa0×\xa010(-3)\xa0±\xa03.09\xa0×\xa010(-3), GDM\xa0=\xa01.01\xa0×\xa010(-3)\xa0±\xa05.86\xa0×\xa010(-4), p\xa0<\xa00.04; NP\xa0=\xa04.53\xa0×\xa010(-3)\xa0±\xa01.62\xa0×\xa010(-3), PP\xa0=\xa03.24\xa0×\xa010(-3)\xa0±\xa01.78\xa0×\xa010(-3)).'] Is β-Cell death decreased in women with gestational diabetes mellitus?