Usefulness of Home Blood Pressure Measurement in the Morning in Type 2 Diabetic Patients: Long-Term Results of a Prospective Longitudinal Study

RESEARCH DESIGN AND METHODS

１.Subjects. After a detailed baseline examination, 400 Japanese subjects were followed up for all-cause mortality and morbidity. All participants visited our clinic regularly. Mean survey duration of all patients was 42.1±20.0 months (range, 3-72 months).Type 2 diabetes was diagnosed according to World Health Organization criteria.At the beginning of the study, 329 patients(82%)were receiving treatment with oral hypoglycemic drugs and/or insulin regimens for diabetes mellitus and 196 patients (49%) were receiving treatment with various anti-hypertensive drugs (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, calcium channel blocker and others) for hypertension. Mean disease duration was 13±8 years (range, 0-40 years). Mean values for other baseline measurements were as follows: BMI,23.7±3.4 kg/m2;HbA1c,6.7±1.1%; triglycerides,150±112 mg/dl;total cholesterol,198±32 mg/dl; LDL,110±29 mg/dl; and HDL,60±19 mg/dl.All patients were fully informed about the purposes and procedures for the study and provided oral consent at enrolment.

2. Baseline and follow-up assessment. Participants were examined using the same methods reported previously (1,2). Briefly, all chemical laboratory data were obtained at each visit without fasting in the morning. BP was measured in the clinic and at home on waking in the morning. Clinic hypertension (CH) and morning hypertension (MH) were defined as systolic BP (SBP)>=130 mmHg and/or diastolic BP (DBP)>=85 mmHg, while clinic normotension (CN) and morning normotension (MN) were defined as SBP <130 mmHg and DBP <86 mmHg, respectively. Microalbuminuria and clinical albuminuria were defined as urinary albumin excretion rate >=30 mg/g creatinine and >=300 mg/g creatinine, respectively.

Microvascular complications were checked for at baseline and every 3 to 6 months throughout the study. Severity of nephropathy was determined using 4 categories: normal; microalbuminuria; clinical albuminuria; and dialysis. Severity of retinopathy was categorized as: normal; non-proliferative retinopathy; pre-proliferative retinopathy; and proliferative retinopathy. Development of changing microvascular events defined according to a change of at least 1 step from baseline (3,4). Macrovascular complications were coronary heart disease (CHD) and cerebrovascular disease (CVD). These events were confirmed by medical history, including contents of treatment. New or worsened (recurrent) events were defined based on clinical manifestations and treatment throughout the study.

At baseline, HT or NTs were determined on the basis of HBP and CBP measurements. Based on HBP, subjects were divided into MH and MN patients, and each endpoint was determined within the survey duration, as defined by the patient displaying sustenance of the same BP status. That is, survey duration varied between individual patients and was defined as the period of time until an MH patient at baseline displayed a change to MN, or until an MN patient at baseline displayed a change to MH. Mean survey duration until endpoints was 29.5±21.1 months(range, 3-72 months).