Nighttime Blood Pressure Assessed Using a Home Monitor in Adolescents and Young Adults With Type 1 Diabetes: Correlation and Agreement With Ambulatory Blood Pressure Monitoring

Objective: To investigate the association of nighttime blood pressure (BP) evaluated using home (HBPM) versus ambulatory monitoring (ABPM) in adolescents and young adults with type 1 diabetes (T1D). Design and method: Individuals aged 12-30 years with T1D underwent 24-hour ABPM (20 min intervals, Microlife WatchBP O3) and HBPM (daytime: duplicate morning and evening measurements; 7 days; night-time: 3 measurements per night for 3 nights; Microlife WatchBP Home-N). Non-dippers were defined as individuals with nighttime systolic and/or diastolic BP fall <10% compared to daytime BP. Results: Data from 91 individuals were analyzed (58% males, mean age 21±5.5 years, body mass index 24±4 kg/m2, HbA1c 7.3±1.0%, T1D duration 11.2±6.5 years, 24h systolic/diastolic ambulatory BP 112±9.4/67±5.7 mmHg, 24h ambulatory hypertension 3.2%). The number of valid measurements (day/night) in ABPM was 45.6±6.5/23.5±6 and in HBPM 23.5±4/8±1.4, respectively (p<0.001/<0.001). Daytime HBPM was slightly lower than ABPM by 1.4±5.6/0.6±4.9 mmHg (systolic/diastolic, p<0.05/NS), but nighttime HBPM was higher by 3.7±6.9/2±5.9 mmHg (p<0.01/<0.01). Strong association was observed between ABPM and HBPM (daytime r=0.84/0.72, nighttime r=0.71/0.52, systolic/diastolic, p<0.001). Good agreement (86%/85%; kappa=0.63/0.59, systolic/diastolic) was found between ABPM and HBPM in diagnosing individuals with elevated nighttime BP (upper quartile of distribution; >109/112 mmHg for systolic and >61/64 mmHg for diastolic BP in ABPM/HBPM respectively). Based on ABPM, 22 participants (25.3%) were classified as non-dippers versus 48 (60.4%) on HBPM (56% agreement; kappa=0.2, p=0.01). Conclusions: In young individuals with T1D, nocturnal HBPM is feasible and strongly correlates with nighttime ABPM. The two methods indicate good agreement in identifying individuals with increased nighttime BP and fair agreement in detecting non-dippers.