Methods of diagnosis of gestational diabetes mellitus are disclosed. In preferred embodiments, a blood sample is obtained from a pregnant female in the 24th to 28th week of pregnancy after an overnight fast, after a 1-hour 50-gram glucose challenge test, or at the 1-hour time point during a 3-hour 100-gram oral glucose tolerance test. The concentrations of fasting plasma glucose and glycosylated plasma proteins in this blood sample are then determined. A fasting plasma glucose concentration equal to or exceeding 90 mg/dL is 100% sensitive and 64% specific in predicting glucose-related macrosomia (i.e., birth weight above 4000 grams). A glycosylated plasma protein concentration equal to or exceeding 23% is 100% sensitive and 52% specific in predicting glucose-related macrosomia. A fasting plasma protein value equal to or exceeding 90 mg/dL and a glycosylated plasma protein value equal to or exceeding 23% is 100% sensitive and 93% specific in predicting glucose-related macrosomia.
