Clustering beyond chance was observed in all four sex/ethnic groups (P < 0.001), with 7% of the sample presenting 30% of the abnormalities in large clusters (> or = 3 abnormalities per individual). The odds ratio (OR) for the association of each abnormality with clustering of the remaining four ranged from 1.6 to 8.8 (P < 0.01). These odds of clustering were notably large in white women. Of the abnormalities, hypertriglyceridemia demonstrated the highest OR (5.0-8.8) and diabetes had the lower OR in African-American subjects than in white subjects (P < 0.001). Insulin, WHR, and BMI were statistically associated with clustering in all groups (P < 0.001, except for BMI in African-Americans.

Fasting plasma glucose is a useful test for the screening of both subcategories of gestational diabetes, a threshold of 85 mg/dl being an acceptable option. Effective screening for the subcategory diabetes can be achieved using a cut point of 89 mg/dl. If greater emphasis is placed on the detection of impaired glucose tolerance, a lower value, 81 mg/dl, may be needed.