Original Articles Ambulatory Blood Pressure in Type I Diabetes Mellitus Comparison to Presence of Incipient Nephropathy in Adolescents and Young Adults WAYNE V. MOORE, DAVID L. DONALDSON, ARNOLD M. CHONKO, PATTI IDEUS, AND THOMAS B. WIEGMANN
AMBP measurements were obtained at 20-min intervals during the day and at 60-min intervals during the night in 38 adolescents and young adults (12-25 yr old) with type I diabetes, and in 36 healthy, nondiabetic control subjects of comparable age. The group of patients with elevated AER (>15 jig/min) had higher mean 24-h sBP, dBP, and BPB (defined as the prevalence of systolic readings >130 mm Hg or diastolic readings >85 mm Hg) compared with both the group of patients with type I diabetes and AER15 were reflected in random BP measurements. Even though the mean random BP measurements of all groups were within the normal range for age, the mean random sBP and dBP of the type I diabetes patients with AER>15 was higher than both the control group and the group with type I diabetes and AER85 mm Hg dBP. BPB was determined for each of the periods. An sBP of 130 mm Hg rather than 135 mm Hg was used because this more accurately reflects the definition of systolic hypertension for this age group (15). GHb was measured by Glyc-Affin GHb assay (Isolab, Akron, OH) in the university clinical laboratory on blood obtained at the time of BP measurement (normal range 6-8.5%, CV range 1.4-3.3%). Results are means ± SD. In the case of group results, the mean AMBP represents the mean of the individual mean BPs. ANOVA was used for multiple comparisons, and Student's nest for unpaired data was used for post hoc comparison of the groups. Day/night comparisons were made using a Student's t test for paired observations. Associations between the measures of AMBP and GFR, RPF, HR, duration of diabetes, and GHb were determined by linear regression analysis. Possible agerelated changes in AMBP were determined by linear regression analysis. RESULTS A comparison of the groups' clinical characteristics revealed no differences between the groups with respect to age, sex distribution, and GHb (Table 1). The duration of diabetes was greater in the group with AER>15 compared with the group with AER15 was significantly greater than both the group with AER15 was significantly greater than the group with AER 15 had lower GFR than the group with AER15, we found a negative association of AER and GFR (r = 0.69, P = 0.0019).
DIABETES, VOL. 41, SEPTEMBER 1992
W.V. MOORE AND ASSOCIATES
TABLE 1 Clinical characteristics of type I diabetes patients and control subjects Type I diabetes patients Pnntrnl
n (M/F) Age of onset (yr) Duration (yr)
subjects
AER < 15
AER > 15
36(19/17) 17.4 ± 2.7 (12.9-25.1) —
27(14/13) 18.2:t3.4 (13.3- - 24.2) 9.1 ±4.3 (1.9--21.7) 12.5 ±3.8 (5.8-- 26.9)
11 (5/6) 18.9 ±5.1 (15.9-25.5) 13.9 ± 5 . 1 * (6.2 - 23.6) 12.7 ±4.0 (8.8 - 21.0)
GHb (%)
—
ANOVA NS 0.006 NS
Values are means ± SE. Numbers in parentheses are the range of values. "Indicates a statistically significant difference from the group with AER < 15.
The means of the measures of AMBP in the groups with A ER > 15 and A ER < 15 were greater than the control group (0.001 < P < 0.01) (Tables 3, 4). The mean 24-h and night sBP and dBP of the group with AER>15 was greater than the group with AER 0.016). The control group had significant 7 and 8 mm Hg decreases in mean sAMBP and dAMBP, respectively, between day and night (P < 0.001) (Table 4). The group with AER15 was not statistically significant. Some of the subjects with AER>15 did exhibit a decrease in BP at night, indicating that the lack of statistical significance may have been secondary to the small number of subjects. Comparison of individual BPBs and AMBPs of the groups indicated overlap in mean 24-h dAMBP and dBPB (Fig. 1). A comparison of the distribution profile of mean sAMBP and sBPB indicated that patients seem to segregate into two groups along these parameters. Patients with AER>15 were consistently higher than those within the AER 15
were at this limit or above, whereas patients with AER15. The 24-h mean HR correlated directly with measures of AMBP in all groups. RPF had a positive association with AMBP in the group with AER15. GFR was associated negatively with measures of AMBP in the group with AER>15. Duration of diabetes was associated positively with measures of AMBP in the entire group and the group with AER< 15, but not with the group with AER>15. The association of various measures of AMBP to age and duration of diabetes were determined to detect possible age-related changes in those measures. The linear regression did indicate age-related increases in the measure of AMBP across the age range of the study population (0.34 < r < 0.58, 0.0001 < P < 0.05). In all instances, measures for the group with AER>15 were increased compared with the group with AER< 15, which were, in turn, elevated with respect to the control group across the age range of the study population.
TABLE 2 Comparison of random BP measurement and renal function of the two groups of type I diabetes patients Pnntrnl wUI III \J\
sBP, random (mm Hg) dBP, random (mm Hg) AER (ixg/min) GFR (ml/min/m2) 2
RPF (ml/min/m )
Type I diabetes patietns
subjects
AER < 15
AER > 15
ANOVA
102 ± 9 (87-123) 59 ± 9 (45 - 69) —
106 ± 11 ( 8 7 - 124) 64 ± 7* (53 - 82) 5.3 ± 3.1 ( 0 . 8 - 13.7) 105 ± 3 2 ( 6 0 - 159) 455 ± 131 (227 - 766)
118 ± 14*t ( 9 8 - 145) 70 ± 7*t (60 - 80) 45.2 ± 32.6 (15.6- 109) 85.0±31.0*t (45-121) 410 ± 8 6 (282 - 633)
AMBP measurements were obtained at 20-min intervals during the day and at 60-min intervals during the night in 38 adolescents and young adults (12-25 yr old) with type I diabetes, and in 36 healthy, nondiabetic control subjects of comparable age. The group of patients with elevated AER (>15 jig/min) had higher mean 24-h sBP, dBP, and BPB (defined as the prevalence of systolic readings >130 mm Hg or diastolic readings >85 mm Hg) compared with both the group of patients with type I diabetes and AER15 were reflected in random BP measurements. Even though the mean random BP measurements of all groups were within the normal range for age, the mean random sBP and dBP of the type I diabetes patients with AER>15 was higher than both the control group and the group with type I diabetes and AER85 mm Hg dBP. BPB was determined for each of the periods. An sBP of 130 mm Hg rather than 135 mm Hg was used because this more accurately reflects the definition of systolic hypertension for this age group (15). GHb was measured by Glyc-Affin GHb assay (Isolab, Akron, OH) in the university clinical laboratory on blood obtained at the time of BP measurement (normal range 6-8.5%, CV range 1.4-3.3%). Results are means ± SD. In the case of group results, the mean AMBP represents the mean of the individual mean BPs. ANOVA was used for multiple comparisons, and Student's nest for unpaired data was used for post hoc comparison of the groups. Day/night comparisons were made using a Student's t test for paired observations. Associations between the measures of AMBP and GFR, RPF, HR, duration of diabetes, and GHb were determined by linear regression analysis. Possible agerelated changes in AMBP were determined by linear regression analysis. RESULTS A comparison of the groups' clinical characteristics revealed no differences between the groups with respect to age, sex distribution, and GHb (Table 1). The duration of diabetes was greater in the group with AER>15 compared with the group with AER15 was significantly greater than both the group with AER15 was significantly greater than the group with AER 15 had lower GFR than the group with AER15, we found a negative association of AER and GFR (r = 0.69, P = 0.0019).
DIABETES, VOL. 41, SEPTEMBER 1992
W.V. MOORE AND ASSOCIATES
TABLE 1 Clinical characteristics of type I diabetes patients and control subjects Type I diabetes patients Pnntrnl
n (M/F) Age of onset (yr) Duration (yr)
subjects
AER < 15
AER > 15
36(19/17) 17.4 ± 2.7 (12.9-25.1) —
27(14/13) 18.2:t3.4 (13.3- - 24.2) 9.1 ±4.3 (1.9--21.7) 12.5 ±3.8 (5.8-- 26.9)
11 (5/6) 18.9 ±5.1 (15.9-25.5) 13.9 ± 5 . 1 * (6.2 - 23.6) 12.7 ±4.0 (8.8 - 21.0)
GHb (%)
—
ANOVA NS 0.006 NS
Values are means ± SE. Numbers in parentheses are the range of values. "Indicates a statistically significant difference from the group with AER < 15.
The means of the measures of AMBP in the groups with A ER > 15 and A ER < 15 were greater than the control group (0.001 < P < 0.01) (Tables 3, 4). The mean 24-h and night sBP and dBP of the group with AER>15 was greater than the group with AER 0.016). The control group had significant 7 and 8 mm Hg decreases in mean sAMBP and dAMBP, respectively, between day and night (P < 0.001) (Table 4). The group with AER15 was not statistically significant. Some of the subjects with AER>15 did exhibit a decrease in BP at night, indicating that the lack of statistical significance may have been secondary to the small number of subjects. Comparison of individual BPBs and AMBPs of the groups indicated overlap in mean 24-h dAMBP and dBPB (Fig. 1). A comparison of the distribution profile of mean sAMBP and sBPB indicated that patients seem to segregate into two groups along these parameters. Patients with AER>15 were consistently higher than those within the AER 15
were at this limit or above, whereas patients with AER15. The 24-h mean HR correlated directly with measures of AMBP in all groups. RPF had a positive association with AMBP in the group with AER15. GFR was associated negatively with measures of AMBP in the group with AER>15. Duration of diabetes was associated positively with measures of AMBP in the entire group and the group with AER< 15, but not with the group with AER>15. The association of various measures of AMBP to age and duration of diabetes were determined to detect possible age-related changes in those measures. The linear regression did indicate age-related increases in the measure of AMBP across the age range of the study population (0.34 < r < 0.58, 0.0001 < P < 0.05). In all instances, measures for the group with AER>15 were increased compared with the group with AER< 15, which were, in turn, elevated with respect to the control group across the age range of the study population.
TABLE 2 Comparison of random BP measurement and renal function of the two groups of type I diabetes patients Pnntrnl wUI III \J\
sBP, random (mm Hg) dBP, random (mm Hg) AER (ixg/min) GFR (ml/min/m2) 2
RPF (ml/min/m )
Type I diabetes patietns
subjects
AER < 15
AER > 15
ANOVA
102 ± 9 (87-123) 59 ± 9 (45 - 69) —
106 ± 11 ( 8 7 - 124) 64 ± 7* (53 - 82) 5.3 ± 3.1 ( 0 . 8 - 13.7) 105 ± 3 2 ( 6 0 - 159) 455 ± 131 (227 - 766)
118 ± 14*t ( 9 8 - 145) 70 ± 7*t (60 - 80) 45.2 ± 32.6 (15.6- 109) 85.0±31.0*t (45-121) 410 ± 8 6 (282 - 633)
