Night blood pressure: relation to organ lesions in microalbuminuric type 1 diabetic patients

Ambulatory blood pressure was measured in 23 microalbuminuric Type 1 diabetic patients without hypertension. Nine patients had a reduction in mean arterial blood (MAP) pressure at night < 10% of their day-time value (non-dippers). The following parameters were measured: glomerular filtration rate (GFR), overnight urinary excretion of albumin (UAE), sodium and potassium, left ventricular dimensions, extracellular volume (ECV), plasma aldosterone, and arginine vasopressin (AVP). Night-time MAP was 11 mmHg lower in patients designated as dippers than in non-dippers. Day-time MAP was similar in dippers (98 +/- 5 mmHg) and non-dippers (99 +/- 8 mmHg, NS). No statistical significant difference was found for UAE in dippers (geometric mean, x/- tolerance factor, microgram min-1) (72 x/- 2.1) vs non-dippers (63 x/- 2.1), for left ventricular mass index (63 +/- 12 vs 59 +/- 10 g m-2), or for GFR (134 +/- 19 vs 148 +/- 22 ml min-1). Aldosterone and AVP were lower in non-dippers (p < 0.05) and a negative correlation in all patients was noticed between ECV and aldosterone (rho = -0.50, p < 0.05). Sodium and potassium excretion and ECV were indistinguishable between the groups. We conclude (1) that impaired reduction of night blood pressure does not seem to be associated with more signs of renal or cardiac lesions and (2) that the lower aldosterone and AVP in non-dippers may counteract volume expansion.