We examined the perinatal outcomes of borderline diabetic pregnant women who had impaired 50 g oral glucose challenge test (OGCT) results, but normal 100 g oral glucose tolerance test (OGTT) results. Our study group included 70 pregnant women who had increased 50 g OGCT results, but normal 100 g OGTT results, and a control group of 122 pregnant women with normal 50 g OGCT results. Polyhydramnios, macrosomia and neonatal birth weight were significantly higher in the study group. After adjusting the results for possibly affecting variables, the risk of polyhydramnios remained significant, while the risk of macrosomia and neonatal birth weight was not significant between the groups. The results from the study group were similar to the control group, when adjusted for other risk factors. Increased 50 g OGCT results in pregnant women can be accepted as a benign state if the 100 g OGTT results are normal.