The incidence of Gestational Diabetes Mellitus (GDM) reported in an out-of-hospital birth center serving 95% Hispanic women was 10%. A program to comanage the care of GDM clients by certified nurse-midwives (CNM) and their physician consultants is described. The antepartum, intrapartum, and neonatal characteristics of 119 GDM clients between 1983 and 1985 is discussed. Intrapartum and newborn transfers to the hospital were similar when the GDM group was compared to the total population serviced by the birth center during 1984. There were no neonatal deaths in the GDM group. Macrosomia did oocur in 26% of the babies of GDM mothers and shoulder dystocia was reported in 7.6%. The results suggest that a quality program can be established to care for GDM mothers in an out-of-hospital birth center. However, ways other than just good glucose control may be necessary to further decrease the incidence of fetal macrosomia.