Hypertension in women with gestational diabetes.

Hypertension in pregnancy and gestational diabetes have in common a lack of universally accepted classification and nomenclature that hinders comparison of data between research groups and contributes to the lack of consensus in the literature on these conditions. The inter-relationship of hypertension and gestational diabetes can be considered from three viewpoints according to whether hypertension is present before, during, or after the pregnancy. The first question is whether hypertension predating pregnancy predisposes to gestational diabetes. Epidemiological evidence and physiological argument based on the common etiologic factor of insulin resistance would suggest that gestational diabetes should be more common in the presence of preexisting hypertension. The limited clinical data available support this hypothesis. There are three issues concerning the coexistence of hypertension and gestational diabetes: whether gestational diabetes predisposes to pregnancy-induced hypertension, whether pregnancy-induced hypertension predisposes to gestational diabetes and what effect the combination has on morbidity and mortality. A number of studies have investigated whether pregnancy-induced hypertension is more common in women with gestational diabetes, but no consensus has been reached. There is little direct clinical evidence on the reverse issue, but data are presented to suggest that pregnancy-induced hypertension may only predispose to gestational diabetes when its etiology is gestational hypertension and not preeclampsia. The issue of how the coexistence of pregnancy-induced hypertension and gestational diabetes affects maternal or neonatal morbidity and mortality is largely unanswered. The last question is whether gestational diabetes has any prognostic significance with regard to the future development of hypertension in the mother. It is well known that gestational diabetes predisposes to subsequent NIDDM and that NIDDM is associated with a high incidence of essential hypertension. Once again insulin resistance may be a unifying factor. However, there is no direct clinical evidence that gestational diabetes predisposes to future hypertension.