Diurnal blood pressure variations in normoalbuminuric type 1 diabetic patients.
OBJECTIVE
To test the hypothesis that normoalbuminuric type 1 diabetic patients segregate into groups with normal and elevated ambulatory blood pressure. To evaluate diurnal variation of blood pressure assessed by individual or fixed night-time periods.


METHODS
Cross-sectional study.


METHODS
Tertiary referral centre.


METHODS
Inclusion criteria for type 1 diabetic patients (n = 33): normal urinary albumin excretion (UAE age < 45 < 20 micrograms min-1), diabetes duration < or = 20 years, age 45 years. Healthy controls (n = 33) were matched for sex and age.


METHODS
Twenty-four hour, day-time, night-time and night/day ratio of ambulatory blood pressure.


RESULTS
Twenty-four-hour blood pressure in diabetic patients did not differ significantly from a normal distribution. The 24-h systolic blood pressure was higher in diabetic patients than in healthy controls (difference: 6 mmHg, 95% confidence interval (CI) from 1 to 10 mmHg, P < 0.05), while no significant differences were found for diastolic values. The 24-h systolic blood pressure in diabetic patients with UAE above the median value (5.8 micrograms min-1) was higher than for those with lower UAE (difference: 7 mmHg, 95% CI from 0.5 to 13 mmHg, P < 0.05). The night/day ratio of diastolic blood pressure based on individual informations of the night period was (mean +/- SD) 80 +/- 6% in diabetic patients and 78 +/- 8% in controls (difference: 2%, 95% CI from -1 to 5%, not significant [NS]). This ratio increase significantly (P < 0.00001) to 90 +/- 5% in diabetes and to 84 +/- 7% in controls if a fixed night period from 22.30 hours to 06.30 hours was assumed.


CONCLUSIONS
It was not possible to identify a well-separated group of normoalbuminuric type 1 diabetic patients with elevated ambulatory blood pressure. Values of UAE above the median in diabetic patients are associated with higher ambulatory blood pressure. Assessment of the night/day variation from fixed time-points should be abandoned because this leads to a serious underestimation of the nocturnal reduction in blood pressure.
Hansen
K W
KW
Medical Department M (Diabetes and Endocrinology), Aarhus Kommunehospital, Denmark.
Pedersen
M M
MM
Christiansen
J S
JS
Mogensen
C E
CE
D000293:Adolescent; D000328:Adult; D000419:Albuminuria / Q000209:etiology; D000553:Ambulatory Care; D001794:Blood Pressure / Q000502:physiology*; D016009:Chi-Square Distribution; D002940:Circadian Rhythm / Q000502:physiology*; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000503:physiopathology*; D003928:Diabetic Nephropathies / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male