['Family history of diabetes is regarded as a risk factor for gestational glucose intolerance. Most selective screening policy includes family history as an indication of oral glucose tolerance test. However, few studies had evaluated the actual incidence of glucose intolerance in this group of women.', 'Pregnant women with oral glucose tolerance test performed for family history of diabetes over two consecutive years were identified. Receiver operating curve was used to identify the age cut-off that give the highest sensitivity and specificity. The incidence of glucose intolerance was compared between women with age above and below this cut-off.', 'One hundred and eighty-seven women were identified. The age cut-off selected was 30.5 years. In young women (age <or= 30 years) with family history alone, the incidence of glucose intolerance is similar to that in the low risk pregnant population (12.5% and 6.3% for 8.0 mmol/L and 9.0 mmol/L cut-off for two hour value of 75 g oral glucose tolerance test, respectively). In women aged above 30 years, the incidence of glucose intolerance raised by three fold (35.2% and 22.0% for 8.0 mmol/L and 9.0 mmol/L cut-off, respectively).'] Is diabetic family history an isolated risk factor for gestational diabetes after 30 years of age?