Insulin resistance and insulin pulsatility in essential hypertension.
OBJECTIVE
Studies in normal humans and in patients with type 2 diabetes mellitus have demonstrated a close inverse relationship between peripheral insulin sensitivity and the frequency of short-term insulin secretory pulses in the systemic circulation. Our objective was to study this relationship in essential hypertension.


METHODS
Study of insulin sensitivity and insulin pulse characteristics in hypertensive subjects and normotensive controls using well-established techniques.


METHODS
Twelve subjects with essential hypertension and 12 age- and sex-matched normotensive controls were recruited. Insulin action was measured using the glucose clamp technique combined with isotope dilution methodology. Insulin pulsatility in the peripheral circulation was assessed by sampling every 2 min for 90 min after an overnight fast Pulses were identified using the computer program Pulsar.


RESULTS
Insulin sensitivity index (glucose infusion rate/ serum insulin) was lower in the hypertensive patients (P= 0.01) and fasting insulin was increased (P= 0.008) compared to controls. The frequency and amplitude of insulin pulses were similar in the two groups. Insulin pulse frequency and insulin sensitivity were inversely related in the normotensive group (r= -0.68, P= 0.015), but not in the hypertensive group (r= -0.23, P= 0.48). Insulin clearance was reduced in the hypertensive group (P= 0.03), and was inversely related to insulin pulse frequency in the two groups combined (r = -0.51, P= 0.01).


CONCLUSIONS
Insulin action was not related to insulin pulse frequency in essential hypertension, in contrast to the situation in normal man.
Wiggam
M I
MI
Sir George E. Clark Metabolic Unit, Royal Victoria Hospital, Belfast, UK.
Hunter
S J
SJ
Armstrong
V L
VL
Ennis
C N
CN
Sheridan
B
B
Atkinson
A B
AB
Bell
P M
PM
D000328:Adult; D005215:Fasting / Q000097:blood; D005260:Female; D006801:Humans; D006973:Hypertension / Q000378:metabolism / Q000503:physiopathology*; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D007333:Insulin Resistance; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D011673:Pulsatile Flow; D012016:Reference Values
D007328:Insulin