Relationship between Circadian Mean Blood Pressure ( MBP ) Rhythm and Microvascular Complications in Normotensive NIDDM Patients

Kim, Hyang; Shim, Seong Chun; Shim, Dae Jung; Lee, Hi Moo; Choi, Yoon Sang; Kang, Jin Ho; Kim, Byung Ik; Lee, Sang Jong; Kim, Yoo Lee; Cho, Yoon Kyung

Abstract

BACKGROUND: Thanks to ambulatory 24-h blood pressure monitoring device, it became possible to investigate circadian pressure rhythm under variable physiologic and pathologic conditions. Moreover, ambulatory 24-h blood pressure has allowed us to detect in diabetic patients unsuspected abnormalities of the blood pressure circadian rhythm and to relate them to autonomic or renal dysfunction. This study was designed to evaluate the relationship between circadian rhythm of mean blood pressure (MBP) and microvascular complications in patients with noninsulin-dependent diabetes mellitus (NIDDM).
METHODS
24hr blood pressure monitoring was applied to 63 normotensive NIDDM patients(mean age 55.3+7.2 year, male: 35, female: 28) who have been hospitalized at our hospital from March 1993 to December 1994 to measure systolic, diastolic and hourly mean pressure of daytime, night time and 24hr. In addition, NIDDM patients were divided into 2 groups according to 24 hour circadian blood pressure rhythm by measuring hourly mean pressure. These 2 groups, group 1 who had a circadian MBP rhythm, with a peak value in the afternoon and group 2 who had an absent or reversed circadian rhythm with a peak value during the night time, were observed to evaluate the frequency of diabetic microvascular complication.
RESULTS
The mean systolic and diastolic ambulatory BP values were significantly higher in the group 2 NIDDM during night-time compared with control group and group 1(systolic pressure: F=12.53 p<0.05 diastolic pressure: F:=15.159 p<0.05). Although there was no significant differences in day-time heart rate between three groups, 1 and 2 group showed significant higher level of night-time heart rate comparing with that of control group (F=3.444 p<0.05). Group 2 diabetes patients showed, both systolic and diastolic, higher night-time and day-time blood pressure ratio(systolic pressure: F=35.958 p<0.05> diastolic pressure F=40.126 p<0.05). Observing the night-time and day-time heart rate ratio, group 1 and 2 patients showed significantly higher level compared with that of cantrol group(F=12.144 p<0.05). Regarding the retmopathy, group 1 patient.; showed mild degree retinopathy or normal finding(X =3.65 p<0.05). However, many group 2 patients showed moderate 2 degree nonproliferative retinopathy(X =3.23 p<0.05). The prevalence of overt nepkuopathy (24-hour urine protein>500mg) and autonomic neuropathy (postural and abnormal E:I ratio during deep breathing test) was significantly higher in group 2 (overt nephropathy: X'=3.23 pCONCLUSION
This study suggests that normotensive NIDDM subjects with absent or reversed circadian MBP rhythms had higher prevalence of microvascular complications than normal circadian rhythm subjects. Absent or reversed circadian rhythm of MBP may be related to the degree of the autonomic neuropathy and microvascular complications..