24-H AMBULATORY BLOOD-PRESSURE, DAYTIME AND NIGHTTIME URINARY ALBUMINAND RETINOL-BINDING PROTEIN EXCRETION IN TYPE-I DIABETIC-PATIENTS

We studied 24-h ambulatory blood pressure (SEP, DBP), actual glycemic control assessed from seven blood glucose measurements, 16-h daytime a nd 8-h nighttime urinary excretion of albumin (UAE) and retinol-bindin g protein (URBP) in 20 normoalbuminuric (group A, nighttime UAE < 20 m u g/min) and 20 microalbuminuric and low-proteinuric type I diabetic p atients (group B, nighttime UAE 20-500 mu g/min) matched for age and d iabetes duration. Glycemic control was similar in the two groups. Dayt ime and nighttime SEP and DBP were higher in group B compared to group A (p < 0.01). Nighttime decrease in SEP and DBP correlated with night time decrease in UAE in group B (p < 0.05, p < 0.001), but not in grou p A. There was no correlation between BP and actual glycemic control i n either group. We found higher daytime and nighttime URBP in group B compared to group A (p < 0.05). We conclude that, in microalbuminuric and low-proteinuric patients, daytime and nighttime BP was elevated bu t still in the normal or borderline range, and nighttime decrease in B P correlated with nighttime decrease in UAE but not with actual glycem ic control. Increased URBP in these patients suggests slightly impaire d proximal tubular function in early stages of diabetic nephropathy.