To estimate the effect of diabetes group prenatal care on rates of preterm birth and large for gestational age (LGA) among patients with diabetes in pregnancy compared with individual diabetes prenatal care. We searched Ovid Medline (1946-), Embase.com (1947-), Scopus (1823-), Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov . We searched electronic databases for randomized controlled trials (RCTs) and observational studies comparing diabetes group prenatal care with individual care among patients with type 2 diabetes mellitus or gestational diabetes mellitus (GDM). The primary outcomes were preterm birth before 37 weeks of gestation and LGA (birth weight at or above the 90th percentile). Secondary outcomes were small for gestational age, cesarean delivery, neonatal hypoglycemia, neonatal intensive care unit admission, breastfeeding at hospital discharge, long-acting reversible contraception (LARC) uptake, and 6-week postpartum visit attendance. Secondary outcomes, limited to the subgroup of patients with GDM, included rates of GDM requiring diabetes medication (A2GDM) and completion of postpartum oral glucose tolerance testing (OGTT). Heterogeneity was assessed with the Cochran Q test and I2 statistic. Random-effects models were used to calculate pooled relative risks (RRs) and weighted mean differences. Eight studies met study criteria and were included in the final analysis: three RCTs and five observational studies. A total of 1,701 patients were included in the pooled studies: 770 (45.3%) in diabetes group prenatal care and 931 (54.7%) in individual care. Patients in diabetes group prenatal care had similar rates of preterm birth compared with patients in individual care (seven studies: pooled rates 9.5% diabetes group prenatal care vs 11.5% individual care, pooled RR 0.77, 95% CI, 0.59-1.01), which held for RCTs and observational studies. There was no difference between diabetes group prenatal care and individual care in rates of LGA overall (four studies: pooled rate 16.7% diabetes group prenatal care vs 20.2% individual care, pooled RR 0.93, 95% CI, 0.59-1.45) or by study type. Rates of other secondary outcomes were similar between diabetes group prenatal care and individual care, except patients in diabetes group prenatal care were more likely to receive postpartum LARC (three studies: pooled rates 46.1% diabetes group prenatal care vs 34.1% individual care, pooled RR 1.44, 95% CI, 1.09-1.91). When analysis was limited to patients with GDM, there were no differences in rates of A2GDM or postpartum visit attendance, but patients in diabetes group prenatal care were significantly more likely to complete postpartum OGTT (five studies: pooled rate 74.0% diabetes group prenatal care vs 49.4% individual care, pooled RR 1.58, 95% CI, 1.19-2.09). Patients with type 2 diabetes and GDM who participate in diabetes group prenatal care have similar rates of preterm birth, LGA, and other pregnancy outcomes compared with those who participate in individual care; however, they are significantly more likely to receive postpartum LARC, and those with GDM are more likely to return for postpartum OGTT. PROSPERO, CRD42021279233.