The objective of the study was to evaluate the effect of a resistance exercise program with an elastic band on insulin requirement and glycemic control in patients with gestational diabetes mellitus (GDM).Sixty-four patients with gestational diabetes mellitus were randomly assigned into 2 groups: an exercise group (EG; n = 32) and a control group not submitted to the exercise program (CG; n = 32).A significant reduction in the number of patients who required insulin was observed in the EG (7/32) compared with the CG group (18/32) (P = .005). The percentage of time spent within the proposed target glucose range (of at least 80% of weekly measurements below the limits preestablished for the disease) was significantly higher in EG compared with the CG group (EG = 0.63 ± 0.30; CG = 0.41 ± 0.31; P = .006).The resistance exercise program was effective in reducing the number of patients with GDM who required insulin and in improving capillary glycemic control in this population.