Implications of Nocturnal Hypertension in Children and Adolescents with Type 1 Diabetes

Introduction:  This study was undertaken to investigate the relationship between nocturnal hypertension and atherosclerosis in children and adolescents with type 1 diabetes:  does nocturnal hypertension affect atherosclerosis in these patients?

Additionally, the study was done to examine the relationship between carotid intima-media thickness (cIMT) and atherogenic risk factors.  cIMT is a useful way to identify subclinical atherosclerosis, and while complications from atherosclerosis generally do not appear until adulthood, atherosclerotic changes at the endothelial level may begin in childhood.  In the presence of atherogenic risk factors, these changes may even progress quickly.

Because cardiovascular disease is such a serious complication of diabetes, it is important to detect these atherogenic risk factors early; therefore, this study was done.

Methods:  Ambulatory blood pressure monitoring (ABPM) was used to identify nocturnal hypertension (hypertension only seen at night).  ABPM and cIMT were measured in 82 children and adolescents with type 1 diabetes.

Researchers also reviewed the following:

Results:  Of the 82 children and adolescents, 43 (52%) were hypertensive; 30 had nocturnal hypertension.

In the nocturnal hypertension group, cIMT was higher than in the normotensive group (0.44 ± 0.03 vs 0.42 ± 0.04 mm; p = 0.026).

There was a group of type 1 diabetic patients who had nonhypertensive blood pressure levels in clinic blood pressure monitoring, and this group was further divided:  patients with nocturnal hypertension when using ABPM and patients without hypertension when using ABPM.  For the nocturnal hypertensive group, cIMT was significantly higher (p = 0.030).  In addition, daytime blood pressure (systolic and diastolic) were significantly higher (p = 0.002 for systolic and p = 0.036 for diastolic).

In multiple linear regression analysis, all ABPM parameters were significantly related to cIMT.

Conclusions:  For children and adolescents with type 1 diabetes and nocturnal hypertension, cIMT is significantly increased, as is daytime blood pressure.  For early detection of diabetes-related macrovascular complications, ABPM may be useful.  The researchers suggest longitudinal studies into what causes nocturnal hypertension and what effect it has on atherosclerosis in type 1 diabetics.

Commentary by Colleen Flynn MD

In normal patients, the blood pressure should dip through the night while sleeping. Elevated daytime and nighttime blood pressure levels are associated with higher rates of cardiovascular disease.

It is not surprising that subjects with nocturnal hypertension, or non-dippers, had higher levels of cIMT, which correlates to vascular injury. Although not recommended routinely in the guidelines, physicians may consider performing ABPM to optimally treat hypertension in patients with type 1 diabetes.