Microvascular correlates of blood pressure, plasma glucose, and insulin resistance in health.
OBJECTIVE
The associations between hypertension, insulin resistance and glucose intolerance are poorly understood. Altered microvascular structure and function could contribute by increasing peripheral vascular resistance and decreasing tissue delivery of glucose. We addressed this hypothesis in a sample of healthy men.


METHODS
We studied 105 healthy young men aged 23-33 years. Insulin resistance was calculated using the Homeostasis Model Assessment (HOMA). Video capillaroscopy was used on the dorsum of the finger to measure skin capillary density, and in nailfold capillaries to measure capillary blood velocity. Skin vasodilatation was measured with laser Doppler fluximetry on the forearm following heating and iontophoresis of acetylcholine.


RESULTS
Higher systolic blood pressure was associated with insulin resistance (r=0.31, P<0.005), lower dermal capillary density (r= -0.25, P<0.05), and impaired maximum dermal blood flow after heating (r= -0.26, P<0.01), but not with capillary blood velocity (r=0.07) or dilator responses to acetylcholine (r=0.09). Insulin resistance did not correlate with indices of microvascular structure or function (all r<+/-0.15). However, higher fasting plasma glucose was associated with lower capillary density (r= -0.27, P<0.01), and increased capillary blood velocity (r=0.30, P<0.05).


CONCLUSIONS
The association between hypertension and insulin resistance is unlikely to be explained by altered microvascular structure and function. However, changes in the microvasculature are found in subjects with early and subtle elevations in blood pressure or fasting plasma glucose in advance of their crossing conventional thresholds for the diagnosis of hypertension or diabetes mellitus.
Irving
R J
RJ
Department of Medical Sciences, Western General Hospital, University of Edinburgh, Edinburgh EH4 2XU, UK.
Walker
B R
BR
Noon
J P
JP
Watt
G C M
GC
Webb
D J
DJ
Shore
A C
AC
D000109:Acetylcholine; D000328:Adult; D000704:Analysis of Variance; D001786:Blood Glucose / Q000378:metabolism*; D001794:Blood Pressure / Q000502:physiology*; D015331:Cohort Studies; D004730:Endothelium, Vascular / Q000502:physiology*; D005385:Fingers / Q000098:blood supply; D005542:Forearm; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008833:Microcirculation / Q000502:physiology; D012867:Skin / Q000098:blood supply; D014665:Vasodilator Agents
D001786:Blood Glucose; D014665:Vasodilator Agents; D000109:Acetylcholine