Acute sodium loading in patients with uncomplicated diabetes mellitus: renal and hormonal effects

1. Diabetes mellitus is associated with high body sodium, but the pathogenetic mechanism is still unknown. The possibility that an abnormal renal handling of sodium, an abnormal responsiveness of sodium-modulating factors or a shift in the set point for sodium metabolism may contribute to or be associated with sodium retention was tested with an acute saline infusion. 2. A consecutive sample of 33 patients with stable non-azotaemic diabetes mellitus (24 insulin-dependent patients) and 30 normal control subjects was studied. Two litres of a 0.9% NaCl infusion were infused over 4 h. The urinary sodium excretion during the infusion and the next 18 h was analysed in relation to blood pressure, creatinine and lithium clearances, Na(+)-K+ co-transport, Na(+)-Li+ countertransport, plasma levels of renin, angiotensin II, aldosterone, noradrenaline, adrenaline, atrial natriuretic factor and digoxin-like factor. 3. Diabetic patients and control subjects did not differ in blood pressure, body mass index, clearances of creatinine, sodium or lithium, intracellular sodium Na(+)-K+ co-transport and Na(+)-Li+ countertransport, urinary and plasma levels of digoxin-like factor, plasma renin activity, angiotensin II, aldosterone, noradrenaline, adrenaline and atrial natriuretic factor. The intravenous saline infusion caused a similar natriuresis in diabetic patients and normal subjects; the renin-angiotensin-aldosterone system was suppressed to a higher degree in diabetic patients than in normal subjects, whereas atrial natriuretic factor was stimulated to a similar extent; plasma digoxin-like activity was unchanged in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)