Blood pressure tracking in adolescents with insulin-dependent diabetes mellitus

Hypertension, one of the most frequent and important complications of insulin-dependent diabetes mellitus (IDDM), usually begins in the second decade of the disease and is rare in childhood. We analysed the blood pressure (BP) levels of 106 patients (48 males, 58 females, aged 2-16 years) in relation to sex and age and we studied the modification of BP with years (tracking). BP levels, registered every three to six months, were compared with the local standard levels for age and expressed as standard deviation scores (SDS) of the means. For each subject a regression line describing the change of the SDS over time was calculated by the method of least squares. The slope of this line is called trend and represents the tendency of BP to increase or decrease with time, i.e. to develop (or not) hypertension. All patients, except one 16 year old girl, had normal BP and no microalbuminuria but ten of them presented with mean levels in the upper quartile and/or a constantly upward BP trend and were considered at risk. After a three year follow-up four of these ten patients became frankly hypertensive with increased microalbuminuria. These results agree with previous findings and with the hypothesis that an increase of intraglomerular and/or systemic BP may precede the appearance of (and even could be responsible for) microalbuminuria. The BP tracking study in IDDM children and adolescents could be useful for an early recognition of patients at risk of developing hypertension and diabetic nephropathy.