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Influence of glucose metabolism on nycthemeral blood pressure variability in hypertensives with an elevated waist-hip ratio
AIR 19:15; 8:426-428
Influence of Glucose Metabolism on Nvcthemeral Blood Pressure Variability in Hypertensives With an Elevated WaIst-Hip Ratio A Link Witfi Arterial Distensibility
"", Jacques Amar, Bernard Chamoniin, Magali Pelissier, Isabelle Garelli, and Michel Salvador
We studied the influence of glucose metabolism on the nycthemeral blood pressure (UP) pattern and arterial distensibility in 33 nontreated hypertensive patients, 45.6 ± 8.5 years old, with elevated waistl hip ratio. Ali patients underwent an ambulatory BP monitoring, a pulse wave velocity (PWV) measurement, and an oral glucose tolerance test. The ratio of mean noctumahdiurnal systolic BP (N/D ratio) was used to assess nycthemeral 13P variability. N/D ratio correlated positively with PWV (r = 0.62; P < .01). When considered according to their glycemic status, N/D ratio and.lJWV were signifi-
cantly higher (P < .05; P < .01) in diabetics and in glucose intolerants compared to patients with normal glucose levels. OUf data indicate that the nycthemeral BP pattern was different according to the metabolic status. The loss of nocturnal decline in BP is associated with carbohydrate disturbances and reduced arterial stiffness. Am J Hypertens 1~95 ;8:42&-428 Nycthemeral BP variability, ambulatory BP monitoring, glucose intolerance, arterial distensibility. KEY WORDS:
he loss of nocturnal decline in blood pres.. sure (BP) has been shown to be associated with stroke and left ventricular hypertro. phy.' A recent study demonstrated that the fall in nocturnal BP was linked to a decrease in sympathetic nerve system activity.' However, the mechanisms which contribute to impair nycthemeral BP pattern in hypertensive patients devoid of autonomicdysfunction, remain unclear. A lackof the nocturnal decline in BP has been found in a group of
elderly hypertensive patients with cardiovascular damage, and was attributed to reduced arterial distensibility." Artorn et al4 showed that smokers have a different circadian BP pattern when compared to nonsmokers and also suggested the role of impaired arterial compliance. It was known that glycemia correlated positively with pulse pressure and carbohydrate disturbances may play a role in the nocturnal decline in BP. The aim of this study was to determine the incidence of glucose metabolism on the nycthemeral BP rhythm and arterialdistensibility in hypertensive patients.
Received June 24, 1994. Accepted October 12, 1994. From the Service de Medecine Interne et d'Hypertension Arterielle, CHU Purpan, Toulouse, France. Address correspondance and reprint requests to Prof. B. Chamontin, Service de Medecine Interneet d'Hypertension Arterielle, PavilIon Turiaf, CHU Purpan, 31059 Toulouse Cedex, France.
POPULATION
T
© 1995 by the American Journal ofHypertensioll, Ltd.
Thirty-three hypertensive patients, 24 men and 9 women (sex ratio 1.26), 45.6 ± 8.5 years old, were studied. No patient had cardiovascular complication.
089.5-70611951$9.50 0895-7061(94)00186-F
AlIi-APRIL 1995-VOL. 8, NO.4, PART 1
NYCTHEMERAI. BP VARIABILITY AND GLUCOSE METABOLISM 4~7
Antihypertensive treatment was stopped 1 week before inclusion. The patients had never taken antidiabetic drugs. Their waist-hip ratio was above 0.95 in men and above 0.85 in women in order to increase the prevalence of glucose intolerance in the study group." There was no evidence of autonomic dysfunction in these patients and no patient had orthostatic hypotension.
METHODS
Blood Pressure Measurements An ambulatory BP measurement was performed in allpatients (SpaceLabs 90207 Monitor, Redmond, WA). BP was measured every 15min during the diurnal period, and every 30 min during the nocturnal period. The ratio of mean nocturnal:diurnal systolic pressure (N/D ratio) was used to assess nycthemeral BP variability. Arterial Distensibility Arterial distensibility was
estimated with the pulse wave velocity (PWV) measurement. PWV was n c1as~,:i.{: index of arterial stiffness. It was measured by means of two pulse transducer heads between the common carotid artery and the right femoral artery. The femoral and carotid pulses were' recorded simultaneously with a paper speed of 200 mm/sec (Gould 8108 Recorder, Gould Electronique, Balainvilliers, France). The distance traveled by the pulse wave was measured over the body surface with a tape measure as a distance between the two recording sites. The distance from the suprasternal notch to the carotid was substracted from the total distance to take into account the pulse travelling in the opposite direction. The foot-to-foot arterial wave velocity was calculated as the ratio between this distance and the time interval separating the feet of the carotid and femoral waves. Casual BP was measured with a mercury sphygmomanometer with cuffs adapted to arm circumference after PWV measurement. Oral Glucose Load An oral glucose tolerance test (75-g glucose load) was carried out in all patients 3 days after an intake of at least 150 g of carbohydrate, Blood samples were performed for the measurement of the glycemia at 0 (gO), 120 min (2 h .- g), and 180 min (3 h - g) min. According to WHO criteria, diabetes mellitus was defined by fasting or 2 h - g higher, respectively, 8 mmol/L and 11 mmollL. Gluccse intolerance was defined by a 2 h - g above 7.8 mmollL. Statistical Analysis Data are expressed as mean ± SD. All univariate and stepwise regression analyses were performedfora populationas a whole using the
least-squares method. Intergroup differences were assessed by unpaired Student's t test.
RESULTS Table 1 shows the clinical characteristics of the patients. Oral glucose load identifies 18 (55%) normoglycemic patients, eight (24%) glucose intolerants, and seven (21 %) diabetics. B:v.lI wasn't different (P ~ .69) between these three groups, respectively, at 29 ± 3.9 kg/m2, 28.6 ± 2.7kg/m2, and 30.1 ± 2.8kg/m2 , As has been described previously we found a positive correlation between PWV, age (r = 0.58; P < .01), and office systolic BP (r = 0.41; P < .05). There was a weak but significant correlation between PWV and fasting glycemia (r = 0.34; P = .05). PWV was significantly higher (P < .01) in diabetics (13.3 ± 2.5 mlsec) or glucose intolerants (11.5 ± 2.6 m1sec) than in patients with normal glucose levels (9.5 ± 1.4 m/sec). Nycthemeral BP cycle was absent (N/D ratio = 1) or inversed (NID > 1)in two patients. N/D ratio correlated positively to age (r = 0.51; P < .01) and PWV (r = 0.62; P < .01). If we considerthree groups according to the glycemic status, NID ratio was significantly higher (P < .05) in diabetics (0.95 ± 0.04) and in glucose intolerants (0.89 ± 0.05) than in patientswith normalglucose level (.56 ± .05). In contrast, there was no difference in N/D and PWV (P = .55, P == .82) between obese (BMI > 30), overweight patients (BMI ~ 25 and :=; 30), and those with normal weight (BMI < 25), In stepwiseregression, PVVV was the only quantitative parameter correlated with N/D (F = 19; P < .01). TABLE 1. CHARACTERISTICS OF THE STUDY POPULAnON (N = 33)
----_._-----------
Age (years) Body mass index (kglm2) Office BP Systolic BP (mm Hg) Diastolic BP (mm Hg) Pulse wave velocity (m/sec) Ambulatory monitoring BP (mm Hg) Daytime Mean systolic BP Mean diastolic BP Nighttime Mean systolic BP Mean diastolic BP Oral glucose load Fasting glycemia (mmol/L) 2-h glycemia (mmol/L) 3-h glycemia (mmoVL)
Mean ± SO
Min-Max
45.66 ± 8.505 29.17 ± 3.42
21-61 23.7-36.1
151.8 ± 20 95.9 ± 10.8 10.8 ± 2.5
114-195 72-120 7-16.3
144.4 ± 14.6 93.6 ± 8.9
117-175 72-108
128.8 ± 18.1 78.9 ± 11.6
102-161 55-100
5.65 ± 1.1 8.14 ± 2.9 5.9 ± 1.7
4.5-9.8 4.6-15.1 2.6-9.8
428 AMAH. ETAL
A/H-APRIL 199.5-VOL. 8, NO.4, PART 1
arterial distensibility related to carbohydrate disturbances. Further studies are needed to support this Our data confirmed the role of carbohydrate disturhypothesis. bances on arterial distensibility. As has been previREFERENCES ously suggested by Kobrin et al, 3 wefounda negative correlation between age, arterial elasticity, and the 1. O'Brien E, Sheridan J, O'Malley K: Dippers and not dippers, Lancet 1988;ii:397. fall in nocturnal BP. Our data indicated that glucose metabolism could exert an influence on the nocturnal 2, Somers VK, Phil D, Dyken ME, et al: Sympatheticnerve activity during sleep in normal subjects. N Engl decline in BP in hypertensive patients with elevated JMed 1993;328:303-307. waist-hip ratio. Nycthemeral BP patternwasdifferent according to metabolism status. The loss of nocturnal 3. Kobrin I, Oigman W, Kuman A: Diurnal variation of blood pressure in elderly patients with essential hyperdecline in B1' was associated with carbohydrate tension. J Am Geriatr Soc 1984;32:896-899. disturbances and reduced arterial distensibility. ABPM is an effective tool to evaluate nycthemeral 4. Artom A, Mela D, Orsoni F, et al: Smoking affects nocturnal blood pressure. JAMA 1991;265:1257. BP variability and this method could be useful to identify hypertensive patients at high metabolic and 5. Dyer AR, Stamler J, Shekelle RB, et al: Pulse pressure-I. Level and associated factors in four Chicago epidemivascular risk From a pathophysiologic point of view ologic studies. JChron Dis 1982i35:259-273. weshowed a strongpositive correlation between nycthemeral BP variability and PVW in our population. 6. Asmar RG, Girerd XJ, Brahimi M, et al: Ambulatory blood pressure measurement, smoking and abnormalKool et al8 demonstrated that the fall in BP duringthe ities of glucose and lipid metabolism in essential hynightcorrelates to an increase in carotid diameter and pertension. J Hypertens 1992;10:181-187. a decrease in pulse pressure. A decline in arterial dis- 7. Fontbonne A, Safar M, and the BIGPRO Study Group: tensibility could modify this mechanism and contribJ Hypertens 1993;9(suppl 6):5423. ute to altering the nycthemeral BP rhythm. 8. Kool MJ, Wijnen JA, Hoeks AP, et al: Diurnal patternof The influence of glucose metabolism on circavessel-wall properties of large arteries in healthy men. dian BP rhythm could be mediated by a decline in J Hypertens 1991;9(supp16):SlO8-S109. DISCUSSION
Influence of Glucose Metabolism on Nvcthemeral Blood Pressure Variability in Hypertensives With an Elevated WaIst-Hip Ratio A Link Witfi Arterial Distensibility
"", Jacques Amar, Bernard Chamoniin, Magali Pelissier, Isabelle Garelli, and Michel Salvador
We studied the influence of glucose metabolism on the nycthemeral blood pressure (UP) pattern and arterial distensibility in 33 nontreated hypertensive patients, 45.6 ± 8.5 years old, with elevated waistl hip ratio. Ali patients underwent an ambulatory BP monitoring, a pulse wave velocity (PWV) measurement, and an oral glucose tolerance test. The ratio of mean noctumahdiurnal systolic BP (N/D ratio) was used to assess nycthemeral 13P variability. N/D ratio correlated positively with PWV (r = 0.62; P < .01). When considered according to their glycemic status, N/D ratio and.lJWV were signifi-
cantly higher (P < .05; P < .01) in diabetics and in glucose intolerants compared to patients with normal glucose levels. OUf data indicate that the nycthemeral BP pattern was different according to the metabolic status. The loss of nocturnal decline in BP is associated with carbohydrate disturbances and reduced arterial stiffness. Am J Hypertens 1~95 ;8:42&-428 Nycthemeral BP variability, ambulatory BP monitoring, glucose intolerance, arterial distensibility. KEY WORDS:
he loss of nocturnal decline in blood pres.. sure (BP) has been shown to be associated with stroke and left ventricular hypertro. phy.' A recent study demonstrated that the fall in nocturnal BP was linked to a decrease in sympathetic nerve system activity.' However, the mechanisms which contribute to impair nycthemeral BP pattern in hypertensive patients devoid of autonomicdysfunction, remain unclear. A lackof the nocturnal decline in BP has been found in a group of
elderly hypertensive patients with cardiovascular damage, and was attributed to reduced arterial distensibility." Artorn et al4 showed that smokers have a different circadian BP pattern when compared to nonsmokers and also suggested the role of impaired arterial compliance. It was known that glycemia correlated positively with pulse pressure and carbohydrate disturbances may play a role in the nocturnal decline in BP. The aim of this study was to determine the incidence of glucose metabolism on the nycthemeral BP rhythm and arterialdistensibility in hypertensive patients.
Received June 24, 1994. Accepted October 12, 1994. From the Service de Medecine Interne et d'Hypertension Arterielle, CHU Purpan, Toulouse, France. Address correspondance and reprint requests to Prof. B. Chamontin, Service de Medecine Interneet d'Hypertension Arterielle, PavilIon Turiaf, CHU Purpan, 31059 Toulouse Cedex, France.
POPULATION
T
© 1995 by the American Journal ofHypertensioll, Ltd.
Thirty-three hypertensive patients, 24 men and 9 women (sex ratio 1.26), 45.6 ± 8.5 years old, were studied. No patient had cardiovascular complication.
089.5-70611951$9.50 0895-7061(94)00186-F
AlIi-APRIL 1995-VOL. 8, NO.4, PART 1
NYCTHEMERAI. BP VARIABILITY AND GLUCOSE METABOLISM 4~7
Antihypertensive treatment was stopped 1 week before inclusion. The patients had never taken antidiabetic drugs. Their waist-hip ratio was above 0.95 in men and above 0.85 in women in order to increase the prevalence of glucose intolerance in the study group." There was no evidence of autonomic dysfunction in these patients and no patient had orthostatic hypotension.
METHODS
Blood Pressure Measurements An ambulatory BP measurement was performed in allpatients (SpaceLabs 90207 Monitor, Redmond, WA). BP was measured every 15min during the diurnal period, and every 30 min during the nocturnal period. The ratio of mean nocturnal:diurnal systolic pressure (N/D ratio) was used to assess nycthemeral BP variability. Arterial Distensibility Arterial distensibility was
estimated with the pulse wave velocity (PWV) measurement. PWV was n c1as~,:i.{: index of arterial stiffness. It was measured by means of two pulse transducer heads between the common carotid artery and the right femoral artery. The femoral and carotid pulses were' recorded simultaneously with a paper speed of 200 mm/sec (Gould 8108 Recorder, Gould Electronique, Balainvilliers, France). The distance traveled by the pulse wave was measured over the body surface with a tape measure as a distance between the two recording sites. The distance from the suprasternal notch to the carotid was substracted from the total distance to take into account the pulse travelling in the opposite direction. The foot-to-foot arterial wave velocity was calculated as the ratio between this distance and the time interval separating the feet of the carotid and femoral waves. Casual BP was measured with a mercury sphygmomanometer with cuffs adapted to arm circumference after PWV measurement. Oral Glucose Load An oral glucose tolerance test (75-g glucose load) was carried out in all patients 3 days after an intake of at least 150 g of carbohydrate, Blood samples were performed for the measurement of the glycemia at 0 (gO), 120 min (2 h .- g), and 180 min (3 h - g) min. According to WHO criteria, diabetes mellitus was defined by fasting or 2 h - g higher, respectively, 8 mmol/L and 11 mmollL. Gluccse intolerance was defined by a 2 h - g above 7.8 mmollL. Statistical Analysis Data are expressed as mean ± SD. All univariate and stepwise regression analyses were performedfora populationas a whole using the
least-squares method. Intergroup differences were assessed by unpaired Student's t test.
RESULTS Table 1 shows the clinical characteristics of the patients. Oral glucose load identifies 18 (55%) normoglycemic patients, eight (24%) glucose intolerants, and seven (21 %) diabetics. B:v.lI wasn't different (P ~ .69) between these three groups, respectively, at 29 ± 3.9 kg/m2, 28.6 ± 2.7kg/m2, and 30.1 ± 2.8kg/m2 , As has been described previously we found a positive correlation between PWV, age (r = 0.58; P < .01), and office systolic BP (r = 0.41; P < .05). There was a weak but significant correlation between PWV and fasting glycemia (r = 0.34; P = .05). PWV was significantly higher (P < .01) in diabetics (13.3 ± 2.5 mlsec) or glucose intolerants (11.5 ± 2.6 m1sec) than in patients with normal glucose levels (9.5 ± 1.4 m/sec). Nycthemeral BP cycle was absent (N/D ratio = 1) or inversed (NID > 1)in two patients. N/D ratio correlated positively to age (r = 0.51; P < .01) and PWV (r = 0.62; P < .01). If we considerthree groups according to the glycemic status, NID ratio was significantly higher (P < .05) in diabetics (0.95 ± 0.04) and in glucose intolerants (0.89 ± 0.05) than in patientswith normalglucose level (.56 ± .05). In contrast, there was no difference in N/D and PWV (P = .55, P == .82) between obese (BMI > 30), overweight patients (BMI ~ 25 and :=; 30), and those with normal weight (BMI < 25), In stepwiseregression, PVVV was the only quantitative parameter correlated with N/D (F = 19; P < .01). TABLE 1. CHARACTERISTICS OF THE STUDY POPULAnON (N = 33)
----_._-----------
Age (years) Body mass index (kglm2) Office BP Systolic BP (mm Hg) Diastolic BP (mm Hg) Pulse wave velocity (m/sec) Ambulatory monitoring BP (mm Hg) Daytime Mean systolic BP Mean diastolic BP Nighttime Mean systolic BP Mean diastolic BP Oral glucose load Fasting glycemia (mmol/L) 2-h glycemia (mmol/L) 3-h glycemia (mmoVL)
Mean ± SO
Min-Max
45.66 ± 8.505 29.17 ± 3.42
21-61 23.7-36.1
151.8 ± 20 95.9 ± 10.8 10.8 ± 2.5
114-195 72-120 7-16.3
144.4 ± 14.6 93.6 ± 8.9
117-175 72-108
128.8 ± 18.1 78.9 ± 11.6
102-161 55-100
5.65 ± 1.1 8.14 ± 2.9 5.9 ± 1.7
4.5-9.8 4.6-15.1 2.6-9.8
428 AMAH. ETAL
A/H-APRIL 199.5-VOL. 8, NO.4, PART 1
arterial distensibility related to carbohydrate disturbances. Further studies are needed to support this Our data confirmed the role of carbohydrate disturhypothesis. bances on arterial distensibility. As has been previREFERENCES ously suggested by Kobrin et al, 3 wefounda negative correlation between age, arterial elasticity, and the 1. O'Brien E, Sheridan J, O'Malley K: Dippers and not dippers, Lancet 1988;ii:397. fall in nocturnal BP. Our data indicated that glucose metabolism could exert an influence on the nocturnal 2, Somers VK, Phil D, Dyken ME, et al: Sympatheticnerve activity during sleep in normal subjects. N Engl decline in BP in hypertensive patients with elevated JMed 1993;328:303-307. waist-hip ratio. Nycthemeral BP patternwasdifferent according to metabolism status. The loss of nocturnal 3. Kobrin I, Oigman W, Kuman A: Diurnal variation of blood pressure in elderly patients with essential hyperdecline in B1' was associated with carbohydrate tension. J Am Geriatr Soc 1984;32:896-899. disturbances and reduced arterial distensibility. ABPM is an effective tool to evaluate nycthemeral 4. Artom A, Mela D, Orsoni F, et al: Smoking affects nocturnal blood pressure. JAMA 1991;265:1257. BP variability and this method could be useful to identify hypertensive patients at high metabolic and 5. Dyer AR, Stamler J, Shekelle RB, et al: Pulse pressure-I. Level and associated factors in four Chicago epidemivascular risk From a pathophysiologic point of view ologic studies. JChron Dis 1982i35:259-273. weshowed a strongpositive correlation between nycthemeral BP variability and PVW in our population. 6. Asmar RG, Girerd XJ, Brahimi M, et al: Ambulatory blood pressure measurement, smoking and abnormalKool et al8 demonstrated that the fall in BP duringthe ities of glucose and lipid metabolism in essential hynightcorrelates to an increase in carotid diameter and pertension. J Hypertens 1992;10:181-187. a decrease in pulse pressure. A decline in arterial dis- 7. Fontbonne A, Safar M, and the BIGPRO Study Group: tensibility could modify this mechanism and contribJ Hypertens 1993;9(suppl 6):5423. ute to altering the nycthemeral BP rhythm. 8. Kool MJ, Wijnen JA, Hoeks AP, et al: Diurnal patternof The influence of glucose metabolism on circavessel-wall properties of large arteries in healthy men. dian BP rhythm could be mediated by a decline in J Hypertens 1991;9(supp16):SlO8-S109. DISCUSSION