Diurnal variation of blood pressure in adolescents with type 1 diabetes: dippers and non-dippers.

The study aimed to determine the prevalence of impaired nocturnal BP fall in adolescents with Type 1 diabetes. Thirty-six normoalbuminuric normotensive adolescents with Type 1 diabetes (19 males, 17 females) aged 14.4 +/- 2.1 years (mean +/- SD) with duration of 4.0 (2.6-7.5) years (median (25-75th percentile)) and 23 controls (11 males, 12 females) aged 15.0 +/- 1.6 years were studied. Day/night BP variation was examined using Ambulatory Accutracker II Monitor (Raleigh, NC). Recordings were made at 30 min intervals during the day and 60 min intervals during the night. Time records were set according to individual diaries. There was no significant difference in day and night systolic or diastolic BP or in mean day/night BP variability between patients with Type 1 diabetes and control subjects. 15/36 patients compared to 3/23 controls (chi squared = 5.43, p < 0.02) were non-dippers defined as a nocturnal fall in either systolic (13/36) or diastolic (6/36) BP or both (4/36) of less than 10%. These non-dippers had normal day-night ratio of heart rate when compared with the remainder of the patients or controls. In conclusion a significant number of young normotensive normoalbuminuric patients with Type 1 diabetes show an impaired fall in blood pressure at night, predominantly in systolic BP. These changes may be relevant to the long-term development of macrovascular or microvascular disease.