Reproducibility of erythrocyte sodium-lithium countertransport activity and ambulatory blood pressure measurements in type 1 diabetes mellitus

We aimed to study the reproducibility of sodium-lithium countertransport [SLCT] activity and ambulatory blood pressure monitoring [ABPM] in type 1 diabetes. We did this by performing repeated measurements of SLCT activity and ABPM in 11 recent-onset diabetic children and in 11 patients with longer duration of diabetes. Both parameters were related to microalbuminuria. In the older group of diabetic children a significant correlation [r = 0.78; P<0.005] in SLCT activity between the first and second study was observed [514.3±186.4 vs 491.0 ± 148.0 μmol/l erythrocytes/h]. Diurnal systolic and diastolic blood pressure were comparable at both time points within the same group of diabetic children [in group 1: 102.6±6.1 vs 108.6±7.6 mmHg N.S.; in group 2: 113.4 ± 10.6 vs 114.0±7.8 mmHg N.S. Diastolic blood pressure in group 1: 57.4±4.8 vs 65.7±6.9 mmHg N.S., in group 2: 70.6±9.1 vs 68.5±5.3 mmHg N.S.]. Moreover, there was a significant correlation in both diurnal and nocturnal systolic blood pressure between the first and second study in the whole diabetic population. Both SLCT activity and blood pressure values obtained by ABPM were found to be reproducible individual characteristic markers in type 1 diabetic children. Received: 22 November 1997 / Accepted in revised form: 30 April 1998