Insulin sensitivity is associated with blood pressure response to sodium in older hypertensives.
The purpose of this study was to determine whether sodium-resistant hypertensives are more insulin resistant and whether dietary sodium restriction improves insulin sensitivity in older hypertensives. Insulin sensitivity was assessed by a frequently sampled intravenous glucose tolerance test to determine the insulin sensitivity index (SI) after 1 wk each of low- (20 mmol.l-1.day-1) and high- (200 mmol.l-1.day-1) sodium diets in 21 older (63 +/- 2 yr) hypertensives. Subjects were grouped on the difference in mean arterial blood pressure (MABP) between diets [sodium sensitive (SS): > or = 5-mmHg increase in MABP on the high-sodium diet (n = 14); sodium resistant (SR): < 5-mmHg increase in MABP on the high-sodium diet (n = 7)]. There was no dietary sodium effect on fasting plasma insulin or SI. An analysis of variance indicated a significant (P = 0.0002) group effect, with SS individuals having lower fasting plasma insulins on the low- (13 +/- 2 vs. 27 +/- 3 microU/ml) and high- (12 +/- 2 vs. 22 +/- 3 microU/ml) sodium diets compared with SR individuals. Similarly, there was a significant (P = 0.0002) group effect in regard to SI, with SS individuals having significantly higher SI on the low- (3.26 +/- 0.60 vs. 0.91 +/- 0.31 microU x 10(-4).min-1.ml-1) and high- (3.45 +/- 0.51 vs. 1.01 +/- 0.30 microU x 10(-4).min-1.ml-1) sodium diets compared with SR individuals. We conclude that SR individuals exhibit a greater degree of insulin resistance than SS individuals and that dietary sodium restriction fails to improve insulin sensitivity regardless of sodium sensitivity status.
Dengel
D R
DR
Department of Internal Medicine, Ann Arbor Veterans Affairs Medical Center, Michigan 48105, USA.
Hogikyan
R V
RV
Brown
M D
MD
Glickman
S G
SG
Supiano
M A
MA
D000368:Aged; D000375:Aging / Q000378:metabolism / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight; D005260:Female; D006801:Humans; D006973:Hypertension / Q000378:metabolism / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D012982:Sodium, Dietary / Q000008:administration & dosage / Q000494:pharmacology*
D001786:Blood Glucose; D007328:Insulin; D012982:Sodium, Dietary