Do Older People Tolerate Ambulatory Blood Pressure Monitoring?

To the Editor: The prevalence of diabetes mellitus has increased rapidly worldwide, partly because of the aging population. It is estimated that one-half to two-thirds of these individuals have postchallenge hyperglycemia without fasting hyperglycemia. Thus, adequate screening of diabetes mellitus relies not only on the fasting glucose test but also largely on postchallenge plasma glucose concentrations. However, the 2-hour oral glucose tolerance test (OGTT) is time consuming, costly, and inconvenient, so we investigated whether one fasting blood with glucose plus hemoglobin (Hb) A1c measurement could provide a more efficient means for identifying diabetes mellitus in elderly persons. Taichung Veterans General Hospital AGing rEsearch group (TCVGHAGE) is a multidisciplinary research group that examines and follows a geriatric cohort consisting mainly of male veterans residing at a government-supported institute in central Taiwan. Most of these veterans came from mainland China and moved to Taiwan along with the government in 1949. This is the baseline study, which was conducted from July 1 to August 30, 2002. Informed consent was obtained from all participants. Participants (369/419) were examined in the morning after at least a 12-hour overnight fast. A 75-g OGTT was administered. HbA1c was measured using boronate-affinity high-performance liquid chromatography (CLC385, Primus Corporation, Kansas City, MO). The interand intraassay coefficients of variation for HbA1c were less than 0.9% and less than 2.9%, respectively. The optimal HbA1c cutoff to maximize sensitivity and specificity corresponding to 2-hour plasma glucose (PG) of 200mg/dL or more was examined using a receiver operating characteristic analysis. We used SPSS for Windows software, release 11.0 (SPSS Inc., Chicago, IL) to analyze the data. A total of 335 participants were subjected to analysis after exclusion of those with chronic renal disfunction, hepatic dysfunction, or missing laboratory data. Their mean standard error of themean age was 79.0 0.2, and body mass index was 23.6 0.6 kg/m. After excluding known diabetic individuals (n5 17), new diabetes mellitus (fasting PG (FPG) 126mg/dL or 2-hour PG 200mg/dL) was found in 76 participants (23.9%). Twenty-six had FPG of 126mg or greater, which yielded a 34.2% sensitivity if FPG was used alone in diabetes mellitus screening. Of the 73 participants whose 2-hour PGwas 200mg/dL or greater, 50 (68.5%) had FPG less than 126mg/dL. Of all participants with FPG less than 126mg/dL, 21 of 42 (50.0%) participants with impaired fasting glucose (IFG) and 29 of 250 (11.6%) participants with normal fasting glucose had a 2-hour PG of 200mg/dL or greater. To estimate the number of subjects who needed additional OGTT, the range ofHbA1c values between a sensitivity of 100% and specificity of 100% in each stratumwas calculated (Table 1). Two hundred thirty-six subjects (80.8%) needed additional OGTT to verify remaining diabetic subjects. This indicated that the combined use of FPGandHbA1c helped to reduce unnecessary OGTT in 56 (19.2%) of 292 individuals. These combinations are most useful in subjects with IFG (84% of subjects with IFG could be spared the OGTT), irrespective of age, body mass index, and values of hemoglobin.