Incidence of pregnancy-induced hypertension among gestational diabetics.

Although hypertensive disorders of pregnancy are more likely to occur in pregestational diabetics, the question of whether they occur more frequently in gestational diabetics or certain subsets of gestational diabetics remains unclear. This study compared 197 gestational diabetics with 197 control patients matched on the basis of age, race, parity, and prepregnancy weight. No significant difference was found between the two groups in the incidence of either pregnancy-induced hypertension or preeclampsia. There was, however, a small but significant elevation in mean arterial blood pressure in the third trimester in gestational diabetics compared with control patients (90.1 versus 87.5 mm Hg; p = 0.006). Mean arterial pressures were also higher in diabetic patients on insulin compared with those on diet, and higher in diabetic patients diagnosed early (less than 24 weeks) compared with those diagnosed late (more than 24 weeks) in pregnancy; however, there were larger numbers of chronic hypertensives in these two groups. We conclude that gestational diabetics do not develop pregnancy-induced hypertension more frequently. Small increases in blood pressure late in pregnancy in these patients achieve statistical significance, but their clinical relevance is unclear.