This study aimed to evaluate the frequency of attenuated decline in nocturnal blood pressure (BP) in diabetic hypertensive patients, and characterize those who don't decrease BP during nighttime. A total of 61 hypertensive patients (26 males and 35 females, mean age 65.8+/-10) were included in the study. Patients were defined as hypertensive if their daytime pressure exceeded 140/90 (the definition relevant at the time of our study) or if they were on antihypertensive treatment. All patients underwent 24 hour Ambulatory BP Monitoring (ABPM) using Suntech Accutracker Dx. Subjects with nocturnal fall in SBP, DBP or MAP of less than 10% of daytime values were classified as non-dippers. Echocardiography and renal function were also evaluated. Two thirds of the subjects were non-dippers. The percentage of dippers among women was higher than that observed in men: SBP 34% versus 19% and DBP 48% versus 38% (the difference is statistically significant with p< 0.01). Non-significant correlation was observed between absence of nocturnal decline, age and gender. The 24 hour ABPM measurements should be recommended in all diabetic hypertensive patients in whom aggressive treatment covering nighttime should be offered.