Source: Diabetes  |  Posted 8 years ago

Diminished nocturnal blood pressure fall in patients with essential hypertension is closely related to left ventricular hypertrophy, and may be influenced by insulin resistance, according to a Japanese comparative study of dippers and nondippers.

Hypertensive patients with diminished nocturnal blood pressure fall are known as nondippers. Studies have shown that patients with nondipper essential hypertension have a poorer prognosis for cardiovascular events as compared to dippers.

Little is known regarding the role of insulin resistance in the development and progression of nondipper essential hypertension. Dr. Futoshi Anan and colleagues at the Oita Medical University, Japan, therefore evaluated the association between nondipper essential hypertension and insulin resistance.

The study included 133 patients with essential hypertension who were, on average, 57 years old. Ambulatory blood pressure was assessed in all patients and determined that 57 patients were dippers and 46 patients were nondippers.

Nocturnal blood pressure fall, left ventricular hypertrophy (LVH), and plasma atrial (ANP) and brain natriuretic peptides (BNP) were assessed. Fasting glucose and insulin levels were also measured.

Systolic and diastolic ambulatory blood pressure at night was higher in patients with nondipper essential hypertension than those with dipper essential hypertension ([]P[] < .0001). Notably though, ambulatory blood pressure was similar between groups during the day.

Nondippers had a significantly higher left ventricular mass index (LVMI) as indicated by echocardiograph, and higher levels of ANP and BNP than that observed in dippers.

Further multivariate analysis revealed that systolic ambulatory blood pressure was significantly associated with LVMI, ANP and BNP. Based on these findings, it appears that diminished nocturnal blood pressure fall may be closely related to the development of LVH and may also cause a concomitant increase in BNP in essential hypertensive patients.

Evaluation of glucose and insulin levels determined that patients with nondipper essential hypertension had higher fasting plasma concentrations of glucose and insulin than those with dipper essential hypertension. Moreover, the homeostasis model assessment (HOMA) index ([]P[] < .0001) was also higher in nondippers.

Multivariate analysis indicated that the HOMA index was a significant factor for LVMI and BNP. This may suggest that insulin resistance plays an important role in the aetiology of nondipper essential hypertension.