Objective      To determine the relationship of blood pressure circadian rhythm and blood pressure variability with carotid atherosclerosis in type 2 diabetes mellitus (T2DM) patients with hypertension.       Methods      A total of 443 T2DM inpatients admitted in our department from January to September 2014 were recruited in this study. They were 250 males and 193 females

at an average age of 60.36±12.11. According the results of ambulatory blood pressure monitoring (ABPM)

the subjects were divided into 3 groups

that is

the normal group (n=158)

the dipper group (n=59) and non-dipper group (n=226). Their blood pressure

blood pressure variability (expressed as standard deviation of blood pressure) and carotid atherosclerosis were compared among the 3 groups. Logistic regression analysis was carried out with the carotid atherosclerosis as the dependent variable.       Results      The incidence of carotid atherosclerosis was 60.6% in the non-dipper group

significantly higher than that in dipper group (42.4%

P0.01). The non-dipper group had significantly higher 24 h systolic blood pressure (24hSBP)

24 h pulse pressure (24hPP)

nighttime SBP (nSBP)

nighttime diastolic blood pressure (nDBP) and nighttime PP (nPP) than the dipper group (P0.01 or P0.05). The standard deviation of the 24hSBP was obviously higher in the non-dipper group than in the dipper group (P0.01). Logistic regression analysis showed that nighttime diastolic blood pressure fall (DBPF) was independently related to carotid atherosclerosis (OR=0.952

95%CI: 0.929～0.975

P0.01).       Conclusion      Non-dipper pattern promotes carotid atherosclerosis in the T2DM patients with hypertension. Nighttime DBPF is a protective factor for carotid atherosclerosis.