Objectives: To determine whether insulin sensitivity is impaired in normotensive offspring of essential hypertensives and to investigate how it relates to disturbed calcium metabolism.
Design: In 10 young lean, normotensive subjects with family histories of essential hypertension and in 10 age-matched controls we investigated insulin sensitivity by the euglycaemic hyperinsulinaemic clamp technique, and 75-g oral glucose tolerance test (GTT). We simultaneously measured calcium-related factors, including the intracellular calcium concentration in platelets.
Results: Insulin-induced glucose uptake was significantly impaired in subjects with positive compared with in subjects with negative family history of essential hypertension. Intracellular calcium concentration was significantly higher in subjects with positive than in those with negative family history. Insulin sensitivity was inversely correlated with intracellular calcium concentration (r = -0.56; P < 0.05). Those who showed a higher intracellular calcium concentration had impaired insulin sensitivity. Oral GTT results were normal in both groups.
Conclusion: Impaired insulin sensitivity and disturbed calcium metabolism exist before the onset of hypertension. Insulin sensitivity correlates inversely with intracellular calcium concentration. These findings suggest that the association of the impaired insulin sensitivity and disturbed calcium metabolism may contribute to the development of hypertension.