Atrial natriuretic factor in hypertensive and normotensive insulin-dependent diabetics

Since insulin increases renal sodium reabsorption, hyperinsulinaemia in insulin-treated insulin-dependent diabetes mellitus might lead to sodium retention and, in turn, increase atrial natriuretic factor (ANF) values. We investigated ANF levels in insulin-dependent diabetes mellitus with and without hypertension. We infused saline (2 mmol/kg per 90 min) in nine normotensive controls, eight normotensive diabetics, seven hypertensive controls and six hypertensive diabetics during the imposition of a euglycaemic glucose clamp with an artificial pancreas. Baseline ANF values were higher in the normotensive and hypertensive diabetics than in the normotensive and hypertensive controls. During a sodium load the sodium excretion rate increased significantly in controls but not in the diabetic groups. The ANF pattern was similar, values being significantly increased in controls and unchanged in diabetic patients. We conclude that euglycaemic, slightly hyperinsulinaemic, insulin-dependent diabetes mellitus patients with and without hypertension are characterized by higher baseline ANF values and an impaired response to an acute saline load as shown by the sodium excretion rate and the plasma ANF concentration.