Increased urinary excretion of digoxin-like immunoreactive substance by insulin-dependent diabetic patients: a linkage with hypertension?

Excretion of digoxin-like immunoreactivity (DLIS) was measured by RIA in timed overnight urine collections from 91 normotensive nondiabetic subjects and 104 normotensive insulin-dependent diabetic (IDDM) patients. The mean +/- SD DLIS excretion rate for the diabetic patients significantly exceeded that for the controls (73 +/- 41 vs 63 +/- 36 pg/min, P = 0.024). In both groups, the mean DLIS excretion rates for men were significantly higher (P = 0.0014, P = 0.006) than for women. In the controls, the DLIS excretion rate significantly correlated with the urinary excretion rate of creatinine (P less than 0.01), Na+ (P less than 0.05), and K+(P less than 0.05), and with the subjects' body weight (P less than 0.01), body mass index (P less than 0.05), and systolic blood pressure (P less than 0.05). In the diabetics, the DLIS excretion rate was significantly correlated with body weight (P less than 0.05) and with urinary excretion rates for albumin (P less than 0.01), creatinine (P less than 0.01), Na+ (P less than 0.05), and K+(P less than 0.05). Our data indicate that: (a) increased amounts of a cardiac glycoside-like substance (or a group of substances) are excreted in the urine of IDDM patients; (b) the urinary excretion of DLIS seems to depend on glomerular filtration rate and physiocochemical properties of glomerular membrane, as well as on subjects' body mass; and (c) because cardiac glycoside-like substances may increase peripheral vascular resistance, increased urinary excretion of DLIS by IDDM patients may indicate a tendency to develop hypertension.